I expect the regulator has asked for a lot of email or messenger comms to investigate something and FB has said "we can't turn over that email, it could contain

I expect the regulator has asked for a lot of email or messenger comms to investigate something and FB has said "we can't turn over that email, it could contain personal stuff that people deal with in their work email". For example if you send your paycheck home via your email, that's a "personal financial document", if you send home a receipt from when you got a flu vaccination that's "employee medical information" and private information about families is when your mom/spouse/whoever emails you at work about something. This is typical in a discovery situation and the lawyers will usually sit down and sift through stuff and figure out what really is relevant, what needs to be redacted/excluded altogether etc.