I’m only sure about it happening with defib/revive when pressing the quick ability key, but might happen with all abilities. When using defib, the ability executes as expected, but afterwards continues executing until switching weapon. Details of this bug may differ, but that’s how I remember it and thought I should report it, before forgetting about it again. Annoying, as it easily leads to being killed if it happens in the wrong situation.
Maybe others remember more details, or maybe it’s been reported anyways. I’ll look into it some more and will try to give a more detailed report if necessary.