Join the ops team at each of those companies, work your way to a position where you can analyze log files, then start analyzing them and see if you can find data that should have been obscured.
I don’t see any way to find out otherwise, we are talking about querying TBs of internal, company specific private logs to see if someone made a mistake. The best anyone could tell you is “I work for company X and I don’t think we’ve had this problem.”
Edit: just using a password manager with unique password for every site will solve most of the problems from a customer perspective. My Facebook password is unique to Facebook and I have 2FA so even an engineer with my password from a log couldn’t login to my account.
> crawling randomly through logs for no good reason is a quick way to get in trouble.
So do you get to or do you not?