Aerizeon
  1. Launch VRChat in VR Mode
  2. Use the shield to force an imposter to be shown on a user in your instance that has a recently generated imposter.
  3. Open your mirror such that the user in question is visible, and move back/forth until each eye receives a slightly different image of the reflected imposter.
This seems to be potentially related to https://feedback.vrchat.com/impostors/p/1381-imposters-have-double-vision-stereo-separation