_VRChatCameraMode indicates an unexpected value when mirrors are in the camera's view.
The shader for the cube in the video draws red if _VRChatCameraMode==1. It works as expected if no mirrors in the camera's view, but it is broken if a mirror appeared.
How to reproduce
  1. Prepare a shader that behaves differently by _VRChatCameraMode
  2. Try to take photo to frame the prepared object and a mirror simultaneously