Has anyone ever seen people dropped from mailing lists randomly? (Build 8902 (May 16, 2024)

I'm getting proper logs that you'd see from "unsubscribing" i.e. 

But I am having many people, over many mailings lists dropped, only one domain so far. It's happening far to often to be accidental.

I have just added notification events and caught the first one this morning, so I'll see just how many happen... right now it's about 15 a week