I have a suspicion that disappearing messages are not deleted but rather only disappear from the UI.
If you read the WhatsApp docs on disappearing messages carefully, you will notices it does not claim that the messages are actually deleted.
Does anyone have any thoughts on what's actually happening with the messages?
When fb released a dedicated page for Messenger, I discover that messages I deleted and which were clearly coming from time when Chat was the default direct messaging feature, were restored and gathered under Messenger dedicated submenu for non-contacts messages.
If they are not actually being deleted then they are violating the European GDPR privacy laws. And I would not be surprised if that was the case. Meta is a terrible corporation when it comes to your privacy and best to avoid their products completely.