For some reason, my project started doing this weird thing where light gets cut off at the seam where a mesh is mirrored. I tried applying the mirror modifier, but nothing is changed. As you can see in the photo, I even added a point light on the other side of the edge and it can't reach past that point. What it is even weirder is that is only started doing this after I installed Filmic Blender https://sobotka.github.io/filmic-blender/ to my version of Blender 2.8. I have tried everything but nothing seems to fix it.
Figured out the problem. I had forgotten to set the normal map node to Non-Colour Data. I am an idiot, but at least I managed to identify the problem in case anyone else has a similar one