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That's definitely the warning for Signal.
It's secure... very secure. If you fuck anything up but have your phone number then you can always access your account and create new messages. But virtually every other scenario is "unless you manually made a backup and have your backup passphrase, then you have lost your chats". Even adding new devices is "your chats will resume here but you cannot see history on a new device".
This is an extreme take on the security vs convenience question... and if you use Signal you need to keep it in mind.
On the pin thing in the end I cleared the cash on my phone. It deleted my messages, but prompted me to sort out my back up.