FIXED - READ BELOW
For some unknown reason, there is a part of my map that looks perfectly fine in Blender and Unity, but after uploading to VRChat the textures start to smear at only this specific angle, in only this direction.
It happens in a few other places, but this is the most visually disgusting.
Here is before, showing the model settings of the .fbx in Unity.
And here you can see the smearing. The angle of the sidewalk showing when it starts and ends.
ONLY AFTER UPLOADING TO VRCHAT!
FIX: Player Settings choose Edit->Project Settings->Player and set Vertex Compression to None.