In the current version of VRChat, the bottom left of the screen seems to have a cursor which triggers the Pointer Enter and Pointer Exit events on Event Trigger components.
Example video VR: (The pointer seems to be slightly outside of the FOV, so it's a bit difficult visualize)
For reference, this also happens on desktop but will probably cause less issues.
The setup looks like the attached screenshot.
This can be quite a problem for creating UIs that are attached to the left hand. I usually disable hand interactions if the hand pointer is over the UI. However, this issue causes that function to trigger whenever the hand is in the wrong position.
Edit 16.5.2023:
A test world is now available (reset button included)