If You stay in the same area for tool long, you will be kicked. If you stand still, despite looking around, shooting, etc., you will be kicked. Previously a player could not be kicked from Prop Hunt, and you still can't if you're a prop, but the hunters have it bad.
With Prop Hint returning there was a 'fix' the developers put out to stop people from farming Depot Credits, because Prop Hunt gives out a dense amount of them per game, especially with 2x Depot Credit events that usually come with the game mode. When playing Prop Hunt as a hunter, you may notice you've been kicked for inactivity, and you think to yourself, 'Well what the hell I was active', well you're not alone. This one is a big issue that needs fixing immediately.