interestingly I got the same notification, checking my passwords I used in those addons showed that they had not been pwned. After another restart the notification did not show up again. I think it was a quirk with the latest update for me.
It’s a new feature in Supervisor 2021.3.0. It compares the passwords you have with an online list of known passwords (known to have been “pwned” or harvested).
From what I see in Supervisor’s log, it seems to perform this check on startup and at 1-hour intervals.
21-03-04 15:50:43 INFO (MainThread) [supervisor.resolution.checks.base] Run check for IssueType.PWNED/ContextType.ADDON
It connects to the following: api.pwnedpasswords.com
I black-listed that address on Pihole in order to silence this feature.