To be more precise: once you see an avatar in an instance and load in its assetbundle, the limits set with Maximum Download Size and Maximum Uncompressed Size won't apply to it for some reason as long as that assetbundle is in memory.
STR
  1. Open VRC
  2. Set your Maximum Download Size and/or Maximum Uncompressed Size to something tiny like 0-10MB
  3. join an instance with other people, observe their impostors
  4. select a person with an impostor, force-show them, and see their full avatar
  5. disable the force show (set avatar display back to the shield)
what should've happened:
  1. the avatar should reload and show the impostor again
what happens:
  1. the avatar 'reloads' (becomes a blue diamond thing for a sec), but loads back in fully visible
This isn't strictly related to force-showing people, it also happens if you lower your settings while in an instance with people that you can already see - no matter how you set these settings, they're gonna keep being visible.
You'd need to hide everyone, or they all would have to change to different avatars, for over a minute to get rid of their assetbundles to see the proper impostors after un-hiding/them switching back.
hiding avatars by performance rank works fine.
noticed it first earlier today on build 1836, and now confirmed it still happens on 1837.