I've been experimenting with a new class feature for Monks, looking at their bonus action contention. So far it seems to work mechanically and is fun to use, but I wonder what it has the potential to break or push over reasonable limits? All feedback really welcome.

Starting at 5th level, you can push yourself beyond your normal limits for a moment. On your turn, you can take one additional bonus action.
Once you use this feature, you must finish a short or long rest before you can use it again. Starting at 17th level, you can use it twice before a rest, but only once on the same turn.