Leadership give u one extra action token. So eg u have three tokens normally but a 4th for leadership. On ur first action u crit miss and ur character takes one damage and loses leadership. Do u lose an action token as the rules say if it’s not showing on the dial on the click ur on u can’t use that ability. And leadership on the pac doesn’t clarify if u keep the token or not

Leadership increases your action total. If the character loses Leadership, you would no longer get the increase to your action total. So in your scenario, you would go back to 3 actions for the turn. If the character somehow regains Leadership your action total would increase back to 4 again.