How do i fix this lit square?!

Does it stay lit when you exit landscape mode?

yes, its always like this. Even when you play it.

Have you tried starting a clean project and editing a terrain to see if it happens again? I tried a few different landscape brushes and configurations to see if I could get that result and have not. If you could detail your process in making this terrain or upload the project to github and i can look at it to see what the problem might be. You can email me the link to @gmail. if you don’t want to publicly post the project

It’s from the photorealistic mountain pack on the marketplace. It does this if you make clean projects using that mountain pack.