If more players try to board the same vehicle (UAZ, BTR-70..) and other players are already in vehicle, the player's character does not board for some reason and is in an intermediate state (out of vehicle). When I was alone and car was empty it never happened.

The player can move (WSAD), but no other actions are available - interaction with world objects, jumping, shooting. interaction with inventory objects (tab). The player's camera is a little different (esp. in peeking out Q/E the angles are shifted way more) and running has about twice the speed.

Only respawn helps.