diff --git a/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/base.py b/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/base.py
index 8f21e8bb6553..e90c2b5be391 100644
--- a/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/base.py
+++ b/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/base.py
@@ -84,6 +84,8 @@ def __init__(
 
         # Save the scopes.
         self._scopes = scopes
+        if not hasattr(self, "_ignore_credentials"):
+            self._ignore_credentials: bool = False
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
@@ -96,7 +98,7 @@ def __init__(
             credentials, _ = google.auth.load_credentials_from_file(
                 credentials_file, **scopes_kwargs, quota_project_id=quota_project_id
             )
-        elif credentials is None:
+        elif credentials is None and not self._ignore_credentials:
             credentials, _ = google.auth.default(
                 **scopes_kwargs, quota_project_id=quota_project_id
             )
diff --git a/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/grpc.py b/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/grpc.py
index ba688559f0ca..4dbf53f3f4a2 100644
--- a/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/grpc.py
+++ b/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/grpc.py
@@ -122,7 +122,8 @@ def __init__(
 
         if isinstance(channel, grpc.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/grpc_asyncio.py b/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/grpc_asyncio.py
index 7620c3319843..3688003b828c 100644
--- a/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/grpc_asyncio.py
+++ b/packages/google-shopping-merchant-notifications/google/shopping/merchant_notifications_v1beta/services/notifications_api_service/transports/grpc_asyncio.py
@@ -169,7 +169,8 @@ def __init__(
 
         if isinstance(channel, aio.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-notifications/noxfile.py b/packages/google-shopping-merchant-notifications/noxfile.py
index 1e6cd48d0529..67b7265f7586 100644
--- a/packages/google-shopping-merchant-notifications/noxfile.py
+++ b/packages/google-shopping-merchant-notifications/noxfile.py
@@ -160,14 +160,28 @@ def install_unittest_dependencies(session, *constraints):
         session.install("-e", ".", *constraints)
 
 
-def default(session):
+@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def unit(session, protobuf_implementation):
     # Install all test dependencies, then install this package in-place.
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
     install_unittest_dependencies(session, "-c", constraints_path)
 
+    # TODO(https://github.com/googleapis/synthtool/issues/1976):
+    # Remove the 'cpp' implementation once support for Protobuf 3.x is dropped.
+    # The 'cpp' implementation requires Protobuf<4.
+    if protobuf_implementation == "cpp":
+        session.install("protobuf<4")
+
     # Run py.test against the unit tests.
     session.run(
         "py.test",
@@ -181,15 +195,12 @@ def default(session):
         "--cov-fail-under=0",
         os.path.join("tests", "unit"),
         *session.posargs,
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
     )
 
 
-@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
-def unit(session):
-    """Run the unit test suite."""
-    default(session)
-
-
 def install_systemtest_dependencies(session, *constraints):
     # Use pre-release gRPC for system tests.
     # Exclude version 1.52.0rc1 which has a known issue.
@@ -358,9 +369,16 @@ def docfx(session):
 
 
 @nox.session(python="3.12")
-def prerelease_deps(session):
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def prerelease_deps(session, protobuf_implementation):
     """Run all tests with prerelease versions of dependencies installed."""
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     # Install all dependencies
     session.install("-e", ".[all, tests, tracing]")
     unit_deps_all = UNIT_TEST_STANDARD_DEPENDENCIES + UNIT_TEST_EXTERNAL_DEPENDENCIES
@@ -397,9 +415,9 @@ def prerelease_deps(session):
         "protobuf",
         # dependency of grpc
         "six",
+        "grpc-google-iam-v1",
         "googleapis-common-protos",
-        # Exclude version 1.52.0rc1 which has a known issue. See https://github.com/grpc/grpc/issues/32163
-        "grpcio!=1.52.0rc1",
+        "grpcio",
         "grpcio-status",
         "google-api-core",
         "google-auth",
@@ -425,4 +443,10 @@ def prerelease_deps(session):
     session.run("python", "-c", "import grpc; print(grpc.__version__)")
     session.run("python", "-c", "import google.auth; print(google.auth.__version__)")
 
-    session.run("py.test", "tests/unit")
+    session.run(
+        "py.test",
+        "tests/unit",
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
+    )
diff --git a/packages/google-shopping-merchant-notifications/setup.py b/packages/google-shopping-merchant-notifications/setup.py
index 14e518a04044..c018d2f6810f 100644
--- a/packages/google-shopping-merchant-notifications/setup.py
+++ b/packages/google-shopping-merchant-notifications/setup.py
@@ -48,7 +48,7 @@
     # See https://github.com/googleapis/google-cloud-python/issues/12364
     "google-auth >= 2.14.1, <3.0.0dev,!=2.24.0,!=2.25.0",
     "proto-plus >= 1.22.3, <2.0.0dev",
-    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
+    "protobuf>=3.20.2,<6.0.0dev,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
     "google-shopping-type >= 0.1.0, <1.0.0dev",
 ]
 url = "https://github.com/googleapis/google-cloud-python/tree/main/packages/google-shopping-merchant-notifications"
diff --git a/packages/google-shopping-merchant-notifications/testing/constraints-3.7.txt b/packages/google-shopping-merchant-notifications/testing/constraints-3.7.txt
index 26e4a9895f74..83bec2765bf7 100644
--- a/packages/google-shopping-merchant-notifications/testing/constraints-3.7.txt
+++ b/packages/google-shopping-merchant-notifications/testing/constraints-3.7.txt
@@ -7,5 +7,5 @@
 google-api-core==1.34.1
 google-auth==2.14.1
 proto-plus==1.22.3
-protobuf==3.19.5
+protobuf==3.20.2
 google-shopping-type==0.1.0
diff --git a/packages/google-shopping-merchant-notifications/tests/unit/gapic/merchant_notifications_v1beta/test_notifications_api_service.py b/packages/google-shopping-merchant-notifications/tests/unit/gapic/merchant_notifications_v1beta/test_notifications_api_service.py
index a797d89a33c5..1b9aed8fa852 100644
--- a/packages/google-shopping-merchant-notifications/tests/unit/gapic/merchant_notifications_v1beta/test_notifications_api_service.py
+++ b/packages/google-shopping-merchant-notifications/tests/unit/gapic/merchant_notifications_v1beta/test_notifications_api_service.py
@@ -1376,12 +1376,7 @@ async def test_get_notification_subscription_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.get_notification_subscription
         ] = mock_object
@@ -1786,12 +1781,7 @@ async def test_create_notification_subscription_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.create_notification_subscription
         ] = mock_object
@@ -2210,12 +2200,7 @@ async def test_update_notification_subscription_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.update_notification_subscription
         ] = mock_object
@@ -2621,12 +2606,7 @@ async def test_delete_notification_subscription_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.delete_notification_subscription
         ] = mock_object
@@ -3007,12 +2987,7 @@ async def test_list_notification_subscriptions_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.list_notification_subscriptions
         ] = mock_object
diff --git a/packages/google-shopping-merchant-products/google/shopping/merchant_products/gapic_version.py b/packages/google-shopping-merchant-products/google/shopping/merchant_products/gapic_version.py
index 33d37a7b677b..558c8aab67c5 100644
--- a/packages/google-shopping-merchant-products/google/shopping/merchant_products/gapic_version.py
+++ b/packages/google-shopping-merchant-products/google/shopping/merchant_products/gapic_version.py
@@ -13,4 +13,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-__version__ = "0.1.0"  # {x-release-please-version}
+__version__ = "0.0.0"  # {x-release-please-version}
diff --git a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/gapic_version.py b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/gapic_version.py
index 33d37a7b677b..558c8aab67c5 100644
--- a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/gapic_version.py
+++ b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/gapic_version.py
@@ -13,4 +13,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-__version__ = "0.1.0"  # {x-release-please-version}
+__version__ = "0.0.0"  # {x-release-please-version}
diff --git a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/base.py b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/base.py
index b4de8e9f999a..4dc6b9c7af16 100644
--- a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/base.py
+++ b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/base.py
@@ -82,6 +82,8 @@ def __init__(
 
         # Save the scopes.
         self._scopes = scopes
+        if not hasattr(self, "_ignore_credentials"):
+            self._ignore_credentials: bool = False
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
@@ -94,7 +96,7 @@ def __init__(
             credentials, _ = google.auth.load_credentials_from_file(
                 credentials_file, **scopes_kwargs, quota_project_id=quota_project_id
             )
-        elif credentials is None:
+        elif credentials is None and not self._ignore_credentials:
             credentials, _ = google.auth.default(
                 **scopes_kwargs, quota_project_id=quota_project_id
             )
diff --git a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/grpc.py b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/grpc.py
index 236b33d28b25..1045506e096b 100644
--- a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/grpc.py
+++ b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/grpc.py
@@ -123,7 +123,8 @@ def __init__(
 
         if isinstance(channel, grpc.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/grpc_asyncio.py b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/grpc_asyncio.py
index 3554c75c29b8..baa48ff8b70e 100644
--- a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/grpc_asyncio.py
+++ b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/product_inputs_service/transports/grpc_asyncio.py
@@ -170,7 +170,8 @@ def __init__(
 
         if isinstance(channel, aio.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/base.py b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/base.py
index 2663e1366a8f..4f680ba16bcb 100644
--- a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/base.py
+++ b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/base.py
@@ -81,6 +81,8 @@ def __init__(
 
         # Save the scopes.
         self._scopes = scopes
+        if not hasattr(self, "_ignore_credentials"):
+            self._ignore_credentials: bool = False
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
@@ -93,7 +95,7 @@ def __init__(
             credentials, _ = google.auth.load_credentials_from_file(
                 credentials_file, **scopes_kwargs, quota_project_id=quota_project_id
             )
-        elif credentials is None:
+        elif credentials is None and not self._ignore_credentials:
             credentials, _ = google.auth.default(
                 **scopes_kwargs, quota_project_id=quota_project_id
             )
diff --git a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/grpc.py b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/grpc.py
index ba1db8627a0e..8cbbc07b5762 100644
--- a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/grpc.py
+++ b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/grpc.py
@@ -122,7 +122,8 @@ def __init__(
 
         if isinstance(channel, grpc.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/grpc_asyncio.py b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/grpc_asyncio.py
index 52d489f4ad98..777f78d87850 100644
--- a/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/grpc_asyncio.py
+++ b/packages/google-shopping-merchant-products/google/shopping/merchant_products_v1beta/services/products_service/transports/grpc_asyncio.py
@@ -169,7 +169,8 @@ def __init__(
 
         if isinstance(channel, aio.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-products/noxfile.py b/packages/google-shopping-merchant-products/noxfile.py
index 1e6cd48d0529..67b7265f7586 100644
--- a/packages/google-shopping-merchant-products/noxfile.py
+++ b/packages/google-shopping-merchant-products/noxfile.py
@@ -160,14 +160,28 @@ def install_unittest_dependencies(session, *constraints):
         session.install("-e", ".", *constraints)
 
 
-def default(session):
+@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def unit(session, protobuf_implementation):
     # Install all test dependencies, then install this package in-place.
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
     install_unittest_dependencies(session, "-c", constraints_path)
 
+    # TODO(https://github.com/googleapis/synthtool/issues/1976):
+    # Remove the 'cpp' implementation once support for Protobuf 3.x is dropped.
+    # The 'cpp' implementation requires Protobuf<4.
+    if protobuf_implementation == "cpp":
+        session.install("protobuf<4")
+
     # Run py.test against the unit tests.
     session.run(
         "py.test",
@@ -181,15 +195,12 @@ def default(session):
         "--cov-fail-under=0",
         os.path.join("tests", "unit"),
         *session.posargs,
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
     )
 
 
-@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
-def unit(session):
-    """Run the unit test suite."""
-    default(session)
-
-
 def install_systemtest_dependencies(session, *constraints):
     # Use pre-release gRPC for system tests.
     # Exclude version 1.52.0rc1 which has a known issue.
@@ -358,9 +369,16 @@ def docfx(session):
 
 
 @nox.session(python="3.12")
-def prerelease_deps(session):
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def prerelease_deps(session, protobuf_implementation):
     """Run all tests with prerelease versions of dependencies installed."""
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     # Install all dependencies
     session.install("-e", ".[all, tests, tracing]")
     unit_deps_all = UNIT_TEST_STANDARD_DEPENDENCIES + UNIT_TEST_EXTERNAL_DEPENDENCIES
@@ -397,9 +415,9 @@ def prerelease_deps(session):
         "protobuf",
         # dependency of grpc
         "six",
+        "grpc-google-iam-v1",
         "googleapis-common-protos",
-        # Exclude version 1.52.0rc1 which has a known issue. See https://github.com/grpc/grpc/issues/32163
-        "grpcio!=1.52.0rc1",
+        "grpcio",
         "grpcio-status",
         "google-api-core",
         "google-auth",
@@ -425,4 +443,10 @@ def prerelease_deps(session):
     session.run("python", "-c", "import grpc; print(grpc.__version__)")
     session.run("python", "-c", "import google.auth; print(google.auth.__version__)")
 
-    session.run("py.test", "tests/unit")
+    session.run(
+        "py.test",
+        "tests/unit",
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
+    )
diff --git a/packages/google-shopping-merchant-products/setup.py b/packages/google-shopping-merchant-products/setup.py
index ae34425da881..9779bc821a80 100644
--- a/packages/google-shopping-merchant-products/setup.py
+++ b/packages/google-shopping-merchant-products/setup.py
@@ -46,7 +46,7 @@
     # See https://github.com/googleapis/google-cloud-python/issues/12364
     "google-auth >= 2.14.1, <3.0.0dev,!=2.24.0,!=2.25.0",
     "proto-plus >= 1.22.3, <2.0.0dev",
-    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
+    "protobuf>=3.20.2,<6.0.0dev,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
     "google-shopping-type >= 0.1.0, <1.0.0dev",
 ]
 url = "https://github.com/googleapis/google-cloud-python/tree/main/packages/google-shopping-merchant-products"
diff --git a/packages/google-shopping-merchant-products/testing/constraints-3.7.txt b/packages/google-shopping-merchant-products/testing/constraints-3.7.txt
index 26e4a9895f74..83bec2765bf7 100644
--- a/packages/google-shopping-merchant-products/testing/constraints-3.7.txt
+++ b/packages/google-shopping-merchant-products/testing/constraints-3.7.txt
@@ -7,5 +7,5 @@
 google-api-core==1.34.1
 google-auth==2.14.1
 proto-plus==1.22.3
-protobuf==3.19.5
+protobuf==3.20.2
 google-shopping-type==0.1.0
diff --git a/packages/google-shopping-merchant-products/tests/unit/gapic/merchant_products_v1beta/test_product_inputs_service.py b/packages/google-shopping-merchant-products/tests/unit/gapic/merchant_products_v1beta/test_product_inputs_service.py
index cf2e5d896113..cc1feddd4b27 100644
--- a/packages/google-shopping-merchant-products/tests/unit/gapic/merchant_products_v1beta/test_product_inputs_service.py
+++ b/packages/google-shopping-merchant-products/tests/unit/gapic/merchant_products_v1beta/test_product_inputs_service.py
@@ -1385,12 +1385,7 @@ async def test_insert_product_input_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.insert_product_input
         ] = mock_object
@@ -1698,12 +1693,7 @@ async def test_delete_product_input_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.delete_product_input
         ] = mock_object
diff --git a/packages/google-shopping-merchant-products/tests/unit/gapic/merchant_products_v1beta/test_products_service.py b/packages/google-shopping-merchant-products/tests/unit/gapic/merchant_products_v1beta/test_products_service.py
index 94fa07a52734..46783ff4a925 100644
--- a/packages/google-shopping-merchant-products/tests/unit/gapic/merchant_products_v1beta/test_products_service.py
+++ b/packages/google-shopping-merchant-products/tests/unit/gapic/merchant_products_v1beta/test_products_service.py
@@ -1323,12 +1323,7 @@ async def test_get_product_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.get_product
         ] = mock_object
@@ -1702,12 +1697,7 @@ async def test_list_products_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.list_products
         ] = mock_object
diff --git a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions/gapic_version.py b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions/gapic_version.py
index 33d37a7b677b..558c8aab67c5 100644
--- a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions/gapic_version.py
+++ b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions/gapic_version.py
@@ -13,4 +13,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-__version__ = "0.1.0"  # {x-release-please-version}
+__version__ = "0.0.0"  # {x-release-please-version}
diff --git a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/gapic_version.py b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/gapic_version.py
index 33d37a7b677b..558c8aab67c5 100644
--- a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/gapic_version.py
+++ b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/gapic_version.py
@@ -13,4 +13,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-__version__ = "0.1.0"  # {x-release-please-version}
+__version__ = "0.0.0"  # {x-release-please-version}
diff --git a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/base.py b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/base.py
index 9a5b6991cc00..b0efda20a322 100644
--- a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/base.py
+++ b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/base.py
@@ -81,6 +81,8 @@ def __init__(
 
         # Save the scopes.
         self._scopes = scopes
+        if not hasattr(self, "_ignore_credentials"):
+            self._ignore_credentials: bool = False
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
@@ -93,7 +95,7 @@ def __init__(
             credentials, _ = google.auth.load_credentials_from_file(
                 credentials_file, **scopes_kwargs, quota_project_id=quota_project_id
             )
-        elif credentials is None:
+        elif credentials is None and not self._ignore_credentials:
             credentials, _ = google.auth.default(
                 **scopes_kwargs, quota_project_id=quota_project_id
             )
diff --git a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/grpc.py b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/grpc.py
index eabb86f93ac1..c60167c4515f 100644
--- a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/grpc.py
+++ b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/grpc.py
@@ -121,7 +121,8 @@ def __init__(
 
         if isinstance(channel, grpc.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/grpc_asyncio.py b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/grpc_asyncio.py
index 36184dc8e6c9..f6f071ffddcf 100644
--- a/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/grpc_asyncio.py
+++ b/packages/google-shopping-merchant-promotions/google/shopping/merchant_promotions_v1beta/services/promotions_service/transports/grpc_asyncio.py
@@ -168,7 +168,8 @@ def __init__(
 
         if isinstance(channel, aio.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-promotions/noxfile.py b/packages/google-shopping-merchant-promotions/noxfile.py
index 1e6cd48d0529..67b7265f7586 100644
--- a/packages/google-shopping-merchant-promotions/noxfile.py
+++ b/packages/google-shopping-merchant-promotions/noxfile.py
@@ -160,14 +160,28 @@ def install_unittest_dependencies(session, *constraints):
         session.install("-e", ".", *constraints)
 
 
-def default(session):
+@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def unit(session, protobuf_implementation):
     # Install all test dependencies, then install this package in-place.
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
     install_unittest_dependencies(session, "-c", constraints_path)
 
+    # TODO(https://github.com/googleapis/synthtool/issues/1976):
+    # Remove the 'cpp' implementation once support for Protobuf 3.x is dropped.
+    # The 'cpp' implementation requires Protobuf<4.
+    if protobuf_implementation == "cpp":
+        session.install("protobuf<4")
+
     # Run py.test against the unit tests.
     session.run(
         "py.test",
@@ -181,15 +195,12 @@ def default(session):
         "--cov-fail-under=0",
         os.path.join("tests", "unit"),
         *session.posargs,
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
     )
 
 
-@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
-def unit(session):
-    """Run the unit test suite."""
-    default(session)
-
-
 def install_systemtest_dependencies(session, *constraints):
     # Use pre-release gRPC for system tests.
     # Exclude version 1.52.0rc1 which has a known issue.
@@ -358,9 +369,16 @@ def docfx(session):
 
 
 @nox.session(python="3.12")
-def prerelease_deps(session):
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def prerelease_deps(session, protobuf_implementation):
     """Run all tests with prerelease versions of dependencies installed."""
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     # Install all dependencies
     session.install("-e", ".[all, tests, tracing]")
     unit_deps_all = UNIT_TEST_STANDARD_DEPENDENCIES + UNIT_TEST_EXTERNAL_DEPENDENCIES
@@ -397,9 +415,9 @@ def prerelease_deps(session):
         "protobuf",
         # dependency of grpc
         "six",
+        "grpc-google-iam-v1",
         "googleapis-common-protos",
-        # Exclude version 1.52.0rc1 which has a known issue. See https://github.com/grpc/grpc/issues/32163
-        "grpcio!=1.52.0rc1",
+        "grpcio",
         "grpcio-status",
         "google-api-core",
         "google-auth",
@@ -425,4 +443,10 @@ def prerelease_deps(session):
     session.run("python", "-c", "import grpc; print(grpc.__version__)")
     session.run("python", "-c", "import google.auth; print(google.auth.__version__)")
 
-    session.run("py.test", "tests/unit")
+    session.run(
+        "py.test",
+        "tests/unit",
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
+    )
diff --git a/packages/google-shopping-merchant-promotions/setup.py b/packages/google-shopping-merchant-promotions/setup.py
index fa22aaf8da2d..3029279654ed 100644
--- a/packages/google-shopping-merchant-promotions/setup.py
+++ b/packages/google-shopping-merchant-promotions/setup.py
@@ -46,7 +46,7 @@
     # See https://github.com/googleapis/google-cloud-python/issues/12364
     "google-auth >= 2.14.1, <3.0.0dev,!=2.24.0,!=2.25.0",
     "proto-plus >= 1.22.3, <2.0.0dev",
-    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
+    "protobuf>=3.20.2,<6.0.0dev,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
     "google-shopping-type >= 0.1.0, <1.0.0dev",
 ]
 url = "https://github.com/googleapis/google-cloud-python/tree/main/packages/google-shopping-merchant-promotions"
diff --git a/packages/google-shopping-merchant-promotions/testing/constraints-3.7.txt b/packages/google-shopping-merchant-promotions/testing/constraints-3.7.txt
index 26e4a9895f74..83bec2765bf7 100644
--- a/packages/google-shopping-merchant-promotions/testing/constraints-3.7.txt
+++ b/packages/google-shopping-merchant-promotions/testing/constraints-3.7.txt
@@ -7,5 +7,5 @@
 google-api-core==1.34.1
 google-auth==2.14.1
 proto-plus==1.22.3
-protobuf==3.19.5
+protobuf==3.20.2
 google-shopping-type==0.1.0
diff --git a/packages/google-shopping-merchant-promotions/tests/unit/gapic/merchant_promotions_v1beta/test_promotions_service.py b/packages/google-shopping-merchant-promotions/tests/unit/gapic/merchant_promotions_v1beta/test_promotions_service.py
index b28f3b66b12e..7f463dcd556c 100644
--- a/packages/google-shopping-merchant-promotions/tests/unit/gapic/merchant_promotions_v1beta/test_promotions_service.py
+++ b/packages/google-shopping-merchant-promotions/tests/unit/gapic/merchant_promotions_v1beta/test_promotions_service.py
@@ -1346,12 +1346,7 @@ async def test_insert_promotion_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.insert_promotion
         ] = mock_object
@@ -1663,12 +1658,7 @@ async def test_get_promotion_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.get_promotion
         ] = mock_object
@@ -2046,12 +2036,7 @@ async def test_list_promotions_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.list_promotions
         ] = mock_object
diff --git a/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/base.py b/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/base.py
index be9af9675f58..176037542c70 100644
--- a/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/base.py
+++ b/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/base.py
@@ -81,6 +81,8 @@ def __init__(
 
         # Save the scopes.
         self._scopes = scopes
+        if not hasattr(self, "_ignore_credentials"):
+            self._ignore_credentials: bool = False
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
@@ -93,7 +95,7 @@ def __init__(
             credentials, _ = google.auth.load_credentials_from_file(
                 credentials_file, **scopes_kwargs, quota_project_id=quota_project_id
             )
-        elif credentials is None:
+        elif credentials is None and not self._ignore_credentials:
             credentials, _ = google.auth.default(
                 **scopes_kwargs, quota_project_id=quota_project_id
             )
diff --git a/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/grpc.py b/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/grpc.py
index bed49c904a50..99b13679bca4 100644
--- a/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/grpc.py
+++ b/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/grpc.py
@@ -122,7 +122,8 @@ def __init__(
 
         if isinstance(channel, grpc.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/grpc_asyncio.py b/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/grpc_asyncio.py
index d55b2b2dbc61..30f1d27c3421 100644
--- a/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/grpc_asyncio.py
+++ b/packages/google-shopping-merchant-quota/google/shopping/merchant_quota_v1beta/services/quota_service/transports/grpc_asyncio.py
@@ -169,7 +169,8 @@ def __init__(
 
         if isinstance(channel, aio.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-quota/noxfile.py b/packages/google-shopping-merchant-quota/noxfile.py
index 1e6cd48d0529..67b7265f7586 100644
--- a/packages/google-shopping-merchant-quota/noxfile.py
+++ b/packages/google-shopping-merchant-quota/noxfile.py
@@ -160,14 +160,28 @@ def install_unittest_dependencies(session, *constraints):
         session.install("-e", ".", *constraints)
 
 
-def default(session):
+@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def unit(session, protobuf_implementation):
     # Install all test dependencies, then install this package in-place.
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
     install_unittest_dependencies(session, "-c", constraints_path)
 
+    # TODO(https://github.com/googleapis/synthtool/issues/1976):
+    # Remove the 'cpp' implementation once support for Protobuf 3.x is dropped.
+    # The 'cpp' implementation requires Protobuf<4.
+    if protobuf_implementation == "cpp":
+        session.install("protobuf<4")
+
     # Run py.test against the unit tests.
     session.run(
         "py.test",
@@ -181,15 +195,12 @@ def default(session):
         "--cov-fail-under=0",
         os.path.join("tests", "unit"),
         *session.posargs,
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
     )
 
 
-@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
-def unit(session):
-    """Run the unit test suite."""
-    default(session)
-
-
 def install_systemtest_dependencies(session, *constraints):
     # Use pre-release gRPC for system tests.
     # Exclude version 1.52.0rc1 which has a known issue.
@@ -358,9 +369,16 @@ def docfx(session):
 
 
 @nox.session(python="3.12")
-def prerelease_deps(session):
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def prerelease_deps(session, protobuf_implementation):
     """Run all tests with prerelease versions of dependencies installed."""
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     # Install all dependencies
     session.install("-e", ".[all, tests, tracing]")
     unit_deps_all = UNIT_TEST_STANDARD_DEPENDENCIES + UNIT_TEST_EXTERNAL_DEPENDENCIES
@@ -397,9 +415,9 @@ def prerelease_deps(session):
         "protobuf",
         # dependency of grpc
         "six",
+        "grpc-google-iam-v1",
         "googleapis-common-protos",
-        # Exclude version 1.52.0rc1 which has a known issue. See https://github.com/grpc/grpc/issues/32163
-        "grpcio!=1.52.0rc1",
+        "grpcio",
         "grpcio-status",
         "google-api-core",
         "google-auth",
@@ -425,4 +443,10 @@ def prerelease_deps(session):
     session.run("python", "-c", "import grpc; print(grpc.__version__)")
     session.run("python", "-c", "import google.auth; print(google.auth.__version__)")
 
-    session.run("py.test", "tests/unit")
+    session.run(
+        "py.test",
+        "tests/unit",
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
+    )
diff --git a/packages/google-shopping-merchant-quota/setup.py b/packages/google-shopping-merchant-quota/setup.py
index 7985790ee73d..237b5e06efaf 100644
--- a/packages/google-shopping-merchant-quota/setup.py
+++ b/packages/google-shopping-merchant-quota/setup.py
@@ -46,7 +46,7 @@
     # See https://github.com/googleapis/google-cloud-python/issues/12364
     "google-auth >= 2.14.1, <3.0.0dev,!=2.24.0,!=2.25.0",
     "proto-plus >= 1.22.3, <2.0.0dev",
-    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
+    "protobuf>=3.20.2,<6.0.0dev,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
 ]
 url = "https://github.com/googleapis/google-cloud-python/tree/main/packages/google-shopping-merchant-quota"
 
diff --git a/packages/google-shopping-merchant-quota/testing/constraints-3.7.txt b/packages/google-shopping-merchant-quota/testing/constraints-3.7.txt
index b8a550c73855..fc812592b0ee 100644
--- a/packages/google-shopping-merchant-quota/testing/constraints-3.7.txt
+++ b/packages/google-shopping-merchant-quota/testing/constraints-3.7.txt
@@ -7,4 +7,4 @@
 google-api-core==1.34.1
 google-auth==2.14.1
 proto-plus==1.22.3
-protobuf==3.19.5
+protobuf==3.20.2
diff --git a/packages/google-shopping-merchant-quota/tests/unit/gapic/merchant_quota_v1beta/test_quota_service.py b/packages/google-shopping-merchant-quota/tests/unit/gapic/merchant_quota_v1beta/test_quota_service.py
index fc750f21b01a..a18ae4f1a674 100644
--- a/packages/google-shopping-merchant-quota/tests/unit/gapic/merchant_quota_v1beta/test_quota_service.py
+++ b/packages/google-shopping-merchant-quota/tests/unit/gapic/merchant_quota_v1beta/test_quota_service.py
@@ -1269,12 +1269,7 @@ async def test_list_quota_groups_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.list_quota_groups
         ] = mock_object
diff --git a/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/base.py b/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/base.py
index 641475368269..c9cc47903f2e 100644
--- a/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/base.py
+++ b/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/base.py
@@ -81,6 +81,8 @@ def __init__(
 
         # Save the scopes.
         self._scopes = scopes
+        if not hasattr(self, "_ignore_credentials"):
+            self._ignore_credentials: bool = False
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
@@ -93,7 +95,7 @@ def __init__(
             credentials, _ = google.auth.load_credentials_from_file(
                 credentials_file, **scopes_kwargs, quota_project_id=quota_project_id
             )
-        elif credentials is None:
+        elif credentials is None and not self._ignore_credentials:
             credentials, _ = google.auth.default(
                 **scopes_kwargs, quota_project_id=quota_project_id
             )
diff --git a/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/grpc.py b/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/grpc.py
index f11ee0caafc5..0e1635e22b97 100644
--- a/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/grpc.py
+++ b/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/grpc.py
@@ -123,7 +123,8 @@ def __init__(
 
         if isinstance(channel, grpc.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/grpc_asyncio.py b/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/grpc_asyncio.py
index 9ad466343658..f714e68e3286 100644
--- a/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/grpc_asyncio.py
+++ b/packages/google-shopping-merchant-reports/google/shopping/merchant_reports_v1beta/services/report_service/transports/grpc_asyncio.py
@@ -170,7 +170,8 @@ def __init__(
 
         if isinstance(channel, aio.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/google-shopping-merchant-reports/noxfile.py b/packages/google-shopping-merchant-reports/noxfile.py
index 1e6cd48d0529..67b7265f7586 100644
--- a/packages/google-shopping-merchant-reports/noxfile.py
+++ b/packages/google-shopping-merchant-reports/noxfile.py
@@ -160,14 +160,28 @@ def install_unittest_dependencies(session, *constraints):
         session.install("-e", ".", *constraints)
 
 
-def default(session):
+@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def unit(session, protobuf_implementation):
     # Install all test dependencies, then install this package in-place.
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
     install_unittest_dependencies(session, "-c", constraints_path)
 
+    # TODO(https://github.com/googleapis/synthtool/issues/1976):
+    # Remove the 'cpp' implementation once support for Protobuf 3.x is dropped.
+    # The 'cpp' implementation requires Protobuf<4.
+    if protobuf_implementation == "cpp":
+        session.install("protobuf<4")
+
     # Run py.test against the unit tests.
     session.run(
         "py.test",
@@ -181,15 +195,12 @@ def default(session):
         "--cov-fail-under=0",
         os.path.join("tests", "unit"),
         *session.posargs,
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
     )
 
 
-@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
-def unit(session):
-    """Run the unit test suite."""
-    default(session)
-
-
 def install_systemtest_dependencies(session, *constraints):
     # Use pre-release gRPC for system tests.
     # Exclude version 1.52.0rc1 which has a known issue.
@@ -358,9 +369,16 @@ def docfx(session):
 
 
 @nox.session(python="3.12")
-def prerelease_deps(session):
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def prerelease_deps(session, protobuf_implementation):
     """Run all tests with prerelease versions of dependencies installed."""
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     # Install all dependencies
     session.install("-e", ".[all, tests, tracing]")
     unit_deps_all = UNIT_TEST_STANDARD_DEPENDENCIES + UNIT_TEST_EXTERNAL_DEPENDENCIES
@@ -397,9 +415,9 @@ def prerelease_deps(session):
         "protobuf",
         # dependency of grpc
         "six",
+        "grpc-google-iam-v1",
         "googleapis-common-protos",
-        # Exclude version 1.52.0rc1 which has a known issue. See https://github.com/grpc/grpc/issues/32163
-        "grpcio!=1.52.0rc1",
+        "grpcio",
         "grpcio-status",
         "google-api-core",
         "google-auth",
@@ -425,4 +443,10 @@ def prerelease_deps(session):
     session.run("python", "-c", "import grpc; print(grpc.__version__)")
     session.run("python", "-c", "import google.auth; print(google.auth.__version__)")
 
-    session.run("py.test", "tests/unit")
+    session.run(
+        "py.test",
+        "tests/unit",
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
+    )
diff --git a/packages/google-shopping-merchant-reports/setup.py b/packages/google-shopping-merchant-reports/setup.py
index f6a5322d9ff1..63375561646a 100644
--- a/packages/google-shopping-merchant-reports/setup.py
+++ b/packages/google-shopping-merchant-reports/setup.py
@@ -46,7 +46,7 @@
     # See https://github.com/googleapis/google-cloud-python/issues/12364
     "google-auth >= 2.14.1, <3.0.0dev,!=2.24.0,!=2.25.0",
     "proto-plus >= 1.22.3, <2.0.0dev",
-    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
+    "protobuf>=3.20.2,<6.0.0dev,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
     "google-shopping-type >= 0.1.0, <1.0.0dev",
 ]
 url = "https://github.com/googleapis/google-cloud-python/tree/main/packages/google-shopping-merchant-reports"
diff --git a/packages/google-shopping-merchant-reports/testing/constraints-3.7.txt b/packages/google-shopping-merchant-reports/testing/constraints-3.7.txt
index 26e4a9895f74..83bec2765bf7 100644
--- a/packages/google-shopping-merchant-reports/testing/constraints-3.7.txt
+++ b/packages/google-shopping-merchant-reports/testing/constraints-3.7.txt
@@ -7,5 +7,5 @@
 google-api-core==1.34.1
 google-auth==2.14.1
 proto-plus==1.22.3
-protobuf==3.19.5
+protobuf==3.20.2
 google-shopping-type==0.1.0
diff --git a/packages/google-shopping-merchant-reports/tests/unit/gapic/merchant_reports_v1beta/test_report_service.py b/packages/google-shopping-merchant-reports/tests/unit/gapic/merchant_reports_v1beta/test_report_service.py
index ec34aaa7841d..d9ae9978a8db 100644
--- a/packages/google-shopping-merchant-reports/tests/unit/gapic/merchant_reports_v1beta/test_report_service.py
+++ b/packages/google-shopping-merchant-reports/tests/unit/gapic/merchant_reports_v1beta/test_report_service.py
@@ -1278,12 +1278,7 @@ async def test_search_async_use_cached_wrapped_rpc(transport: str = "grpc_asynci
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.search
         ] = mock_object
diff --git a/packages/google-shopping-type/google/shopping/type/gapic_version.py b/packages/google-shopping-type/google/shopping/type/gapic_version.py
index 51d2795b9d6b..558c8aab67c5 100644
--- a/packages/google-shopping-type/google/shopping/type/gapic_version.py
+++ b/packages/google-shopping-type/google/shopping/type/gapic_version.py
@@ -13,4 +13,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-__version__ = "0.1.6"  # {x-release-please-version}
+__version__ = "0.0.0"  # {x-release-please-version}
diff --git a/packages/google-shopping-type/noxfile.py b/packages/google-shopping-type/noxfile.py
index 1e6cd48d0529..67b7265f7586 100644
--- a/packages/google-shopping-type/noxfile.py
+++ b/packages/google-shopping-type/noxfile.py
@@ -160,14 +160,28 @@ def install_unittest_dependencies(session, *constraints):
         session.install("-e", ".", *constraints)
 
 
-def default(session):
+@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def unit(session, protobuf_implementation):
     # Install all test dependencies, then install this package in-place.
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
     install_unittest_dependencies(session, "-c", constraints_path)
 
+    # TODO(https://github.com/googleapis/synthtool/issues/1976):
+    # Remove the 'cpp' implementation once support for Protobuf 3.x is dropped.
+    # The 'cpp' implementation requires Protobuf<4.
+    if protobuf_implementation == "cpp":
+        session.install("protobuf<4")
+
     # Run py.test against the unit tests.
     session.run(
         "py.test",
@@ -181,15 +195,12 @@ def default(session):
         "--cov-fail-under=0",
         os.path.join("tests", "unit"),
         *session.posargs,
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
     )
 
 
-@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
-def unit(session):
-    """Run the unit test suite."""
-    default(session)
-
-
 def install_systemtest_dependencies(session, *constraints):
     # Use pre-release gRPC for system tests.
     # Exclude version 1.52.0rc1 which has a known issue.
@@ -358,9 +369,16 @@ def docfx(session):
 
 
 @nox.session(python="3.12")
-def prerelease_deps(session):
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def prerelease_deps(session, protobuf_implementation):
     """Run all tests with prerelease versions of dependencies installed."""
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     # Install all dependencies
     session.install("-e", ".[all, tests, tracing]")
     unit_deps_all = UNIT_TEST_STANDARD_DEPENDENCIES + UNIT_TEST_EXTERNAL_DEPENDENCIES
@@ -397,9 +415,9 @@ def prerelease_deps(session):
         "protobuf",
         # dependency of grpc
         "six",
+        "grpc-google-iam-v1",
         "googleapis-common-protos",
-        # Exclude version 1.52.0rc1 which has a known issue. See https://github.com/grpc/grpc/issues/32163
-        "grpcio!=1.52.0rc1",
+        "grpcio",
         "grpcio-status",
         "google-api-core",
         "google-auth",
@@ -425,4 +443,10 @@ def prerelease_deps(session):
     session.run("python", "-c", "import grpc; print(grpc.__version__)")
     session.run("python", "-c", "import google.auth; print(google.auth.__version__)")
 
-    session.run("py.test", "tests/unit")
+    session.run(
+        "py.test",
+        "tests/unit",
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
+    )
diff --git a/packages/google-shopping-type/setup.py b/packages/google-shopping-type/setup.py
index 59008ebea125..e0c14fe5f9cf 100644
--- a/packages/google-shopping-type/setup.py
+++ b/packages/google-shopping-type/setup.py
@@ -44,7 +44,7 @@
     # See https://github.com/googleapis/google-cloud-python/issues/12364
     "google-auth >= 2.14.1, <3.0.0dev,!=2.24.0,!=2.25.0",
     "proto-plus >= 1.22.3, <2.0.0dev",
-    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
+    "protobuf>=3.20.2,<6.0.0dev,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
 ]
 url = "https://github.com/googleapis/google-cloud-python/tree/main/packages/google-shopping-type"
 
diff --git a/packages/google-shopping-type/testing/constraints-3.7.txt b/packages/google-shopping-type/testing/constraints-3.7.txt
index b8a550c73855..fc812592b0ee 100644
--- a/packages/google-shopping-type/testing/constraints-3.7.txt
+++ b/packages/google-shopping-type/testing/constraints-3.7.txt
@@ -7,4 +7,4 @@
 google-api-core==1.34.1
 google-auth==2.14.1
 proto-plus==1.22.3
-protobuf==3.19.5
+protobuf==3.20.2
diff --git a/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/base.py b/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/base.py
index d9f52a686267..235bc55bcf5d 100644
--- a/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/base.py
+++ b/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/base.py
@@ -82,6 +82,8 @@ def __init__(
 
         # Save the scopes.
         self._scopes = scopes
+        if not hasattr(self, "_ignore_credentials"):
+            self._ignore_credentials: bool = False
 
         # If no credentials are provided, then determine the appropriate
         # defaults.
@@ -94,7 +96,7 @@ def __init__(
             credentials, _ = google.auth.load_credentials_from_file(
                 credentials_file, **scopes_kwargs, quota_project_id=quota_project_id
             )
-        elif credentials is None:
+        elif credentials is None and not self._ignore_credentials:
             credentials, _ = google.auth.default(
                 **scopes_kwargs, quota_project_id=quota_project_id
             )
diff --git a/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/grpc.py b/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/grpc.py
index d5276021efd5..7ebadac51ede 100644
--- a/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/grpc.py
+++ b/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/grpc.py
@@ -137,7 +137,8 @@ def __init__(
 
         if isinstance(channel, grpc.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/grpc_asyncio.py b/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/grpc_asyncio.py
index 88c2154684f1..12f24288228c 100644
--- a/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/grpc_asyncio.py
+++ b/packages/grafeas/grafeas/grafeas_v1/services/grafeas/transports/grpc_asyncio.py
@@ -184,7 +184,8 @@ def __init__(
 
         if isinstance(channel, aio.Channel):
             # Ignore credentials if a channel was passed.
-            credentials = False
+            credentials = None
+            self._ignore_credentials = True
             # If a channel was explicitly provided, set it.
             self._grpc_channel = channel
             self._ssl_channel_credentials = None
diff --git a/packages/grafeas/noxfile.py b/packages/grafeas/noxfile.py
index 6b6c0cbeab51..35fd05608ec5 100644
--- a/packages/grafeas/noxfile.py
+++ b/packages/grafeas/noxfile.py
@@ -160,14 +160,28 @@ def install_unittest_dependencies(session, *constraints):
         session.install("-e", ".", *constraints)
 
 
-def default(session):
+@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def unit(session, protobuf_implementation):
     # Install all test dependencies, then install this package in-place.
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
     install_unittest_dependencies(session, "-c", constraints_path)
 
+    # TODO(https://github.com/googleapis/synthtool/issues/1976):
+    # Remove the 'cpp' implementation once support for Protobuf 3.x is dropped.
+    # The 'cpp' implementation requires Protobuf<4.
+    if protobuf_implementation == "cpp":
+        session.install("protobuf<4")
+
     # Run py.test against the unit tests.
     session.run(
         "py.test",
@@ -181,15 +195,12 @@ def default(session):
         "--cov-fail-under=0",
         os.path.join("tests", "unit"),
         *session.posargs,
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
     )
 
 
-@nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
-def unit(session):
-    """Run the unit test suite."""
-    default(session)
-
-
 def install_systemtest_dependencies(session, *constraints):
     # Use pre-release gRPC for system tests.
     # Exclude version 1.52.0rc1 which has a known issue.
@@ -358,9 +369,16 @@ def docfx(session):
 
 
 @nox.session(python="3.12")
-def prerelease_deps(session):
+@nox.parametrize(
+    "protobuf_implementation",
+    ["python", "upb", "cpp"],
+)
+def prerelease_deps(session, protobuf_implementation):
     """Run all tests with prerelease versions of dependencies installed."""
 
+    if protobuf_implementation == "cpp" and session.python in ("3.11", "3.12"):
+        session.skip("cpp implementation is not supported in python 3.11+")
+
     # Install all dependencies
     session.install("-e", ".[all, tests, tracing]")
     unit_deps_all = UNIT_TEST_STANDARD_DEPENDENCIES + UNIT_TEST_EXTERNAL_DEPENDENCIES
@@ -397,9 +415,9 @@ def prerelease_deps(session):
         "protobuf",
         # dependency of grpc
         "six",
+        "grpc-google-iam-v1",
         "googleapis-common-protos",
-        # Exclude version 1.52.0rc1 which has a known issue. See https://github.com/grpc/grpc/issues/32163
-        "grpcio!=1.52.0rc1",
+        "grpcio",
         "grpcio-status",
         "google-api-core",
         "google-auth",
@@ -425,4 +443,10 @@ def prerelease_deps(session):
     session.run("python", "-c", "import grpc; print(grpc.__version__)")
     session.run("python", "-c", "import google.auth; print(google.auth.__version__)")
 
-    session.run("py.test", "tests/unit")
+    session.run(
+        "py.test",
+        "tests/unit",
+        env={
+            "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,
+        },
+    )
diff --git a/packages/grafeas/setup.py b/packages/grafeas/setup.py
index b9c4a380924d..77f4956769c6 100644
--- a/packages/grafeas/setup.py
+++ b/packages/grafeas/setup.py
@@ -44,7 +44,7 @@
     # See https://github.com/googleapis/google-cloud-python/issues/12364
     "google-auth >= 2.14.1, <3.0.0dev,!=2.24.0,!=2.25.0",
     "proto-plus >= 1.22.3, <2.0.0dev",
-    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
+    "protobuf>=3.20.2,<6.0.0dev,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
 ]
 url = "https://github.com/googleapis/google-cloud-python/tree/main/packages/grafeas"
 
diff --git a/packages/grafeas/testing/constraints-3.7.txt b/packages/grafeas/testing/constraints-3.7.txt
index b8a550c73855..fc812592b0ee 100644
--- a/packages/grafeas/testing/constraints-3.7.txt
+++ b/packages/grafeas/testing/constraints-3.7.txt
@@ -7,4 +7,4 @@
 google-api-core==1.34.1
 google-auth==2.14.1
 proto-plus==1.22.3
-protobuf==3.19.5
+protobuf==3.20.2
diff --git a/packages/grafeas/tests/unit/gapic/grafeas_v1/test_grafeas.py b/packages/grafeas/tests/unit/gapic/grafeas_v1/test_grafeas.py
index 270553bf5142..f83258acece8 100644
--- a/packages/grafeas/tests/unit/gapic/grafeas_v1/test_grafeas.py
+++ b/packages/grafeas/tests/unit/gapic/grafeas_v1/test_grafeas.py
@@ -258,12 +258,7 @@ async def test_get_occurrence_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.get_occurrence
         ] = mock_object
@@ -637,12 +632,7 @@ async def test_list_occurrences_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.list_occurrences
         ] = mock_object
@@ -1209,12 +1199,7 @@ async def test_delete_occurrence_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.delete_occurrence
         ] = mock_object
@@ -1601,12 +1586,7 @@ async def test_create_occurrence_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.create_occurrence
         ] = mock_object
@@ -2002,12 +1982,7 @@ async def test_batch_create_occurrences_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.batch_create_occurrences
         ] = mock_object
@@ -2410,12 +2385,7 @@ async def test_update_occurrence_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.update_occurrence
         ] = mock_object
@@ -2837,12 +2807,7 @@ async def test_get_occurrence_note_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.get_occurrence_note
         ] = mock_object
@@ -3230,12 +3195,7 @@ async def test_get_note_async_use_cached_wrapped_rpc(transport: str = "grpc_asyn
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.get_note
         ] = mock_object
@@ -3605,12 +3565,7 @@ async def test_list_notes_async_use_cached_wrapped_rpc(transport: str = "grpc_as
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.list_notes
         ] = mock_object
@@ -4167,12 +4122,7 @@ async def test_delete_note_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.delete_note
         ] = mock_object
@@ -4541,12 +4491,7 @@ async def test_create_note_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.create_note
         ] = mock_object
@@ -4941,12 +4886,7 @@ async def test_batch_create_notes_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.batch_create_notes
         ] = mock_object
@@ -5339,12 +5279,7 @@ async def test_update_note_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.update_note
         ] = mock_object
@@ -5749,12 +5684,7 @@ async def test_list_note_occurrences_async_use_cached_wrapped_rpc(
         )
 
         # Replace cached wrapped function with mock
-        class AwaitableMock(mock.AsyncMock):
-            def __await__(self):
-                self.await_count += 1
-                return iter([])
-
-        mock_object = AwaitableMock()
+        mock_object = mock.AsyncMock()
         client._client._transport._wrapped_methods[
             client._client._transport.list_note_occurrences
         ] = mock_object