This 11+ year old answer states that per-site moderator access to the following information about individual users is logged:
real name
email
IP address
Notwithstanding the need to keep certain functionality secret to avoid users gaming the system and other (abhorrent) abuses:
- does anyone actually look at these logs, and do they serve any on-going purpose or are they just dead-end datasets?
Bonus question...
- Is access to my PII by SO Staff / CMs also logged and monitored?