Strange visual glitch in editor game view top corner

Hi, I’m having a really strange glitch in the top-left corner of my editor window. There seems to be a strip, about say 20pixels high and 100 pixels long, that seems as if it’s Z-fighting with itself (which shouldn’t be happening as not only are no two elements on the same Z plane, but most elements are rendered by different cameras).

Any insight as to what’s going on? Here’s a gif:



Did you ever figure this out? I’m getting something similar. I have a hunch it could be related to broken script references on prefabs, but just not sure.