Another user can free-move (Tab) the 3rd person camera very close to you as long as there are no colliders between you - range seems to be about 5x avatar height. If you're within that range, they can get up close without you knowing, and while the scroll wheel may have discrete steps, moving their avatar allows precise camera positioning arbitrarily close.

Photo/stream cameras already get a visible indicator for similar reasons.

Idea: maybe if their camera is much closer to another player's avatar than it is to them, apply one or more of:

* show an icon (camera-style) to that player

* don't render the too-close avatar in the 3rd person view (personal space style) (edit: maybe prioritising hips given the possible sensitivity)

* force the avatar render layer's clipping plane to the same effect — though this without point (2) could allow for strategic clipping and would be more disruptive to screenshots