From f483b3b852a7736cb157e50b8d8a258cd8180a9a Mon Sep 17 00:00:00 2001
From: Daniel Richards <daniel.richards@automattic.com>
Date: Mon, 6 Sep 2021 12:58:51 +0800
Subject: [PATCH 1/2] Mark side effecty code as not persistent change

---
 packages/block-library/src/navigation-link/edit.js | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/packages/block-library/src/navigation-link/edit.js b/packages/block-library/src/navigation-link/edit.js
index fa93ace9b5de5..95a60fbbb61f4 100644
--- a/packages/block-library/src/navigation-link/edit.js
+++ b/packages/block-library/src/navigation-link/edit.js
@@ -291,7 +291,10 @@ export default function NavigationLinkEdit( {
 	};
 	const { showSubmenuIcon } = context;
 	const { saveEntityRecord } = useDispatch( coreStore );
-	const { insertBlock } = useDispatch( blockEditorStore );
+	const {
+		insertBlock,
+		__unstableMarkNextChangeAsNotPersistent,
+	} = useDispatch( blockEditorStore );
 	const [ isLinkOpen, setIsLinkOpen ] = useState( false );
 	const listItemRef = useRef( null );
 	const isDraggingWithin = useIsDraggingWithin( listItemRef );
@@ -354,8 +357,10 @@ export default function NavigationLinkEdit( {
 		[ clientId ]
 	);
 
-	// Store the colors from context as attributes for rendering
-	useEffect( () => setAttributes( { isTopLevelLink } ), [ isTopLevelLink ] );
+	useEffect( () => {
+		__unstableMarkNextChangeAsNotPersistent();
+		setAttributes( { isTopLevelLink } );
+	}, [ isTopLevelLink ] );
 
 	/**
 	 * Insert a link block when submenu is added.

From 48cb892cd04d7dd9dcbed182072a30b132065fc7 Mon Sep 17 00:00:00 2001
From: Daniel Richards <daniel.richards@automattic.com>
Date: Mon, 6 Sep 2021 13:16:13 +0800
Subject: [PATCH 2/2] Add comment

---
 packages/block-library/src/navigation-link/edit.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/block-library/src/navigation-link/edit.js b/packages/block-library/src/navigation-link/edit.js
index 95a60fbbb61f4..fce0a339b2e25 100644
--- a/packages/block-library/src/navigation-link/edit.js
+++ b/packages/block-library/src/navigation-link/edit.js
@@ -358,6 +358,10 @@ export default function NavigationLinkEdit( {
 	);
 
 	useEffect( () => {
+		// This side-effect should not create an undo level as those should
+		// only be created via user interactions. Mark this change as
+		// not persistent to avoid undo level creation.
+		// See https://github.com/WordPress/gutenberg/issues/34564.
 		__unstableMarkNextChangeAsNotPersistent();
 		setAttributes( { isTopLevelLink } );
 	}, [ isTopLevelLink ] );