currently groups get never deleted on server side. according to @pavel-mayer this is to guarantee that every client (even long absent ones) is notified about the non-existence of the group. Nevertheless we should have a cleanup every 6 / 12 month on none-existent groups.
nearby groups are handled different and can probably be deleted as soon as they enter state "none" (check handling on client).
currently groups get never deleted on server side. according to @pavel-mayer this is to guarantee that every client (even long absent ones) is notified about the non-existence of the group. Nevertheless we should have a cleanup every 6 / 12 month on none-existent groups. nearby groups are handled different and can probably be deleted as soon as they enter state "none" (check handling on client).