Fix insertion point animation (#35729)

packages/block-editor/src/components/block-tools/insertion-point.js

@@ -291,6 +291,9 @@ function InsertionPointPopover( {
 			// Render in the old slot if needed for backward compatibility,
 			// otherwise render in place (not in the the default popover slot).
 			__unstableSlotName={ __unstablePopoverSlot || null }
+			// Forces a remount of the popover when its position changes
+			// This makes sure the popover doesn't animate from its previous position.
+			key={ nextClientId + '--' + rootClientId }
 		>
 			<motion.div
 				layout={ ! disableMotion }