Update release note

releasenotes/notes/vf2layout-preset-passmanager-db46513a24e79aa9.yaml

@@ -2,21 +2,47 @@
 upgrade:
   - |
     The preset passmanagers in :mod:`qiskit.transpiler.preset_passmanagers`
-    for all optimization levels above 0 have been changed to run the
-    :class:`~qiskit.transpiler.passes.VF2Layout` by default prior to the layout
-    pass. The :class:`~qiskit.transpiler.passes.VF2Layout` pass will quickly
-    check if a perfect layout can be found and superscedes what was previously
+    for all optimization levels 2 and 3 as generated by
+    :func:`~qiskit.transpiler.preset_passmanagers.level_2_pass_manager` and
+    :func:`~qiskit.transpiler.preset_passmanagers.level_3_pass_manager` have
+    been changed to run the :class:`~qiskit.transpiler.passes.VF2Layout` by
+    default prior to the layout pass. The
+    :class:`~qiskit.transpiler.passes.VF2Layout` pass will quickly check if
+    a perfect layout can be found and superscedes what was previously
     done for optimization levels 2 and 3 which were using a combination of
     :class:`~qiskit.transpiler.passes.TrivialLayout` and
     :class:`~qiskit.transpiler.passes.CSPLayout` to try and find a perfect
-    layout. However, because :class:`~qiskit.transpiler.passes.VF2Layout` is
-    fast even in the failure mode it has been added to level 1 as
-    well to improve the quality of the results. This will result in potentially
-    different behavior when :func:`~qiskit.compiler.transpile` is called by
-    default as it removes a default path for all optimization levels >=1
-    of using a trivial layout (where ``circuit.qubits[0]`` is mapped to physical
-    qubit 0, ``circuit.qubits[1]`` is mapped to physical qubit 1, etc) assuming
-    the trivial layout is perfect. If your use case was dependent on the
+    layout. This will result in potentially different behavior when
+    :func:`~qiskit.compiler.transpile` is called by default as it removes a
+    default path for all optimization levels >=2 of using a trivial layout
+    (where ``circuit.qubits[0]`` is mapped to physical qubit 0,
+    ``circuit.qubits[1]`` is mapped to physical qubit 1, etc) assuming the
+    trivial layout is perfect. If your use case was dependent on the
     trivial layout you can explictly request it when transpiling by specifying
     ``layout_method="trivial"`` when calling :func:`~qiskit.compiler.transpile`.
-
+  - |
+    The preset pass manager for optimization level 1 (when calling
+    :func:`~qiskit.compiler.transpile` with ``optimization_level=1`` or when
+    no ``optimization_level`` argument is set) as generated by
+    :func:`~qiskit.transpiler.preset_passmanagers.level_1_pass_manager` has
+    been changed so that :class:`~qiskit.transpiler.passes.VF2Layout` is
+    called by default to quickly check if a a perfect layout can be found
+    prior to the :class:`~qiskit.transpiler.passes.DenseLayout`. However,
+    unlike with optimization level 2 and 3 a trivial layout is attempted
+    prior to running :class:`~qiskit.transpiler.passes.VF2Layout` and if
+    it's a perfect mapping this will be used instead.
+deprecations:
+  - |
+    For the preset pass manager for optimization level 1 (when calling
+    :func:`~qiskit.compiler.transpile` with ``optimization_level=1`` or
+    no ``optimization_level`` argument set) as generated by
+    :func:`~qiskit.transpiler.preset_passmanagers.level_1_pass_manager` the
+    implict default of running ::class:`~qiskit.transpiler.passes.TrivialLayout`
+    and using the trivial layout if it's a perfect match is deprecated
+    and this behavior will change in a future release. A ``FutureWarning`` is
+    now emitted whenever a trivial layout is used by default with optimization
+    level 1. This means that :func:`~qiskit.compiler.transpile` by default may
+    emit a ``FutureWarning`` if it picks a trivial layout as a result of this
+    current behavior. If this default towards a trivial layout is desired you
+    can explicitly request it when transpiling by specifying
+    ``layout_method="trivial"`` when calling :func:`~qiskit.compiler.transpile`.