I honestly have no idea if this can even be fixed but I did some tests (thanks @Story and @Livvv for being my unvolentary volunteers) and I realized that players with high ping (200+) have about 10 seconds after joining a lobby where they can see ALL players and npcs in the tab menu, including vanished staff. If there is any way to fix this then i believe it should be fixed because it kinda compromises a staff members vanish.
didnt work, i will upload tomorrow when i can get on my computer