This wasn't a disappearing messages case, this was a case where they had uninstalled Signal entirely, including all their messages. But Apple was storing the received message text from the notification in its local database. I don't think it is edge case, in that if someone uninstalls their Whatsapp or Signal or whatever, or they delete a chat/message within that app, that it should be gone off your phone. The OS storing end to end encrypted message content in notification history for no reason (why store content in a database at all) makes message deletion work differently than most people would expect, so it doesn't feel like an edge case to me.

Signal (at least on iOS) has a setting called "Notification Content" which defaults (unsafely in the light of this bug) to "Name, content, and Actions", but allows you to select either "Name Only" or "No Name or Content".

I assume that "Name only" option results in the push notification only sending "Signal message from Bob", and the "No Name or Content" one only sending "You have a new Signal message" - instead of the whole "Signal message from Bob: Let's rob the bank tomorrow!"

If I could have it work the way I'd prefer, Signal would let me set those Notification Content on a per contact and per chat basis - so I could set my bank robbing crew and group chats to "No Name or Content" while leaving mom and the family group chat on "Name, content, and Actions".

(But realistically, if I _did_ have a bank robbing crew they'd all be on my burner phone, not the phone I do family group chat with.)