Description of the problem
I updated from r100 to r104, and somewhere along the way, something went wrong with IBL setup: fully rough materials have light artefacts (and that even in parts which are occluded by occlusion maps). It’s especially visible on dark materials.
Because of this, it is impossible to get the feeling of dark fabric for example, since the material always has some reflection.
See this fully black, fully rough product comparison. The only light in the scene is an EXR envMap used for IBL. This also happens when using a JPG envMap for IBL, so I’m thinking it might have something to do with the CubeMap generator…
And here is a minimal reproduction of the issue, where light artefacts are visible on the torus mesh, making it look like it has reflections while it should be fully rough: https://jsfiddle.net/4er2nxwt/