Fix useZoomOut hook behavior

packages/block-editor/src/hooks/use-zoom-out.js

@@ -2,7 +2,7 @@
  * WordPress dependencies
  */
 import { useSelect, useDispatch } from '@wordpress/data';
-import { useEffect } from '@wordpress/element';
+import { useEffect, useRef } from '@wordpress/element';
 
 /**
  * Internal dependencies
@@ -20,14 +20,20 @@ export function useZoomOut( zoomOut = true ) {
 		useDispatch( blockEditorStore )
 	);
 	const { isZoomOut } = unlock( useSelect( blockEditorStore ) );
+	const isZoomOutOnMountRef = useRef();
 
 	useEffect( () => {
-		const isZoomOutOnMount = isZoomOut();
+		isZoomOutOnMountRef.current = isZoomOut();
 
 		return () => {
-			if ( isZoomOutOnMount ) {
-				setZoomLevel( 50 );
-			} else {
+			// If we zoomed out for the user, and we are still in zoom out on unmount,
+			// return them to the default zoom level.
+			// - Open Inserter
+			// - Switch to pattern tab
+			// - Sets Zoom level 50
+			// - Close inserter
+			// - Zoom level resets to 100
+			if ( ! isZoomOutOnMountRef.current && isZoomOut() ) {
 				resetZoomLevel();
 			}
 		};
@@ -36,8 +42,14 @@ export function useZoomOut( zoomOut = true ) {
 	useEffect( () => {
 		if ( zoomOut ) {
 			setZoomLevel( 50 );
-		} else {
+		}
+		// Only reset zoom level if we were not in zoom out on mount:
+		// - Enter Zoom Level 50
+		// - Open inserter
+		// - Switch to Blocks Tab
+		// - Zoom level 50 should be persisted
+		else if ( ! zoomOut && ! isZoomOutOnMountRef.current ) {
 			resetZoomLevel();
 		}
-	}, [ zoomOut, setZoomLevel, resetZoomLevel ] );
+	}, [ zoomOut, setZoomLevel, resetZoomLevel, isZoomOutOnMountRef ] );
 }