Overnight I had two unsubscriptions (from different people and different groups) reported to me by email.
One is all fine, it was from a (paid) subgroup. The person remains a member of the main (announcement) group and there is an entry in the subgroup activity log saying "... left, via web"
The other is rather less satisfactory, indeed a #bug IMHO. It was from a standalone free group and while I can find an activity log entry from when the person accepted my invitation to join, there is no activity log entry for the departure.
Malcolm Austen - email: email@example.com