On our realm we have a large map wall (40x40 approx). With the new shaders update this wall now makes the screen flash until the game is fully restarted. This behavior has been experienced on both Windows and Xbox versions of Bedrock.
The behavior persists even into the menu.
Im also having this issue aswell with a 33 by 33 map with more than 1000 individual maps. I think around a 300 map (17x17) limit is what the shaders can handle for survival. But i found out if you are in creative and you set your chunks with the map in it to be always loaded with the /tickingarea command it'll fix the issue.