JohnGruszczyk
If user invites (using calendar in Outlook or Teams, not by sending just the link) an extra person to recurring meeting for one day. Then the default option should be isolation. By that I mean, a person is unable to see chats/files from past, neither in future after the meeting.
Also for a single meeting, if you invite group of people into the meeting and they are starting to chat before the actual meeting start. If organizer removes one of attendee after that, that ex-attendee should lose her/his access to the files and the chat as well.
Another question is, if organizer should have possibilities to override the default behavior. But even if that is not possible, it would be much easier to explain to the users why the person is losing her/his access to chat/files. Today as Teams is not working in that way, we are forced to explain why a person being not anymore invited is still a participate on the chat. Explaining that to security teams or compliance teams is even more harder job, as you might guess.