Weird artifacts while rendering

Hello everyone, I’m relatively new to blender and have encountered some odd artifacts on one particular object in a scene. It seems to be some kind of darkening that occurs along the tiles that Blender uses to break apart a frame while rendering.

I’ve checked for overlapping vertices, but there were none to remove. I also tried recalculating the normals as well as flipping their direction. It’s just a simple cube that is actually sitting a minute distance away from the wall behind it.

As you can see in the pictures, it occurs both with and without any materials or textures applied. This is driving me nuts. Hopefully it’s just something simple I’m overlooking. Any help would be appreciated.

It looks like planes are intersecting that big one.