Question about subject of activity update notification e-mail

Please tell me about email notification of activities.
I noticed that a notification mail arrived for unintended people. I thought that my own recognition was incorrect about the timing of mail notification. I thought that only the files and folders owned by my account were eligible. Somehow we received update notification of group not belonging.

Group has AAA group, group B only for calendar. Important users can see AAA, and normal (BBB) users share only calendars.

A user who belongs only to the group BBB users have received update notifications about the files/folders shared by AAA.
Please tell me how to keep mail to AAA and stop AAA update notification to BBB.

Please help,

Nextcloud 14.0.1