Any new user added to the calender will get a copy of the calendar in the state they were added to it, but then any new events will not sync to them after they've been added.
So, in the current state, users who were granted access to the calendar before the user was removed are still able to use and sync the calendar. PROBLEM: New users who are added will see the appointments added to the calendar up to that point, but any new appointments added by any user will not be seen by the new user. From what I can tell, the situation for us appears to be as follows:
I'm seeing a similar problem in my organization.