(Case 1108912) Extra GPU Skinning calls and bound internal Geometry Shader that should not be there

When updating the project to 2018.3, we have stumbled upon an issue where we get extra GPU Skinning calls and all standard surface shaders have an extra Geometry Shader bound with no resource attached (texBones), which is probably connected to the extra GPU Skinning calls, that are shown under the Camera.Render section in RenderDoc captures.

This has been happening in both the late betas, as well as latest RC, and happens in built player. Not sure about earlier betas.

I attached RenderDoc captures from the 2018.2, 2018.3 where it's not OK and 2018.3 where it's OK (which is random, but happens much much less when we render a depth map for weather effects first).

Unfortunately, I'm not sure how to isolate the issue to provide a repro case. But I don't believe that our code can somehow keep the Unity's GS attached, or cause more GPU skinning calls anyways? :/

Also, turning off the GPU Skinning solves the issue, but I'd like a proper solution.