Hey, the good news is that tells us that Lumen is more than likely not related. That shortens the scope quite a bit.
Does distance to the wall affect it?
Also have you tried adjusting the overall graphic settings?
Play around with these a little bit. That warning you’re getting is directly related to rendering and lighting, so it’s going to be hard to get perfect. But if you turn up or down some settings you could get it to go away!