Ah right. Caveat though that that applies if Messages is set to use iCloud. In that case iCloud backup backs up the decryption key to ensure you don't inadverte

Ah right. Caveat though that that applies if Messages is set to use iCloud. In that case iCloud backup backs up the decryption key to ensure you don't inadvertently lose access to the messages because they're end to end encrypted. If Messages is not toggled in iCloud, then as long as iCloud backup is toggled, it will directly back up the raw messages - encrypting with an Apple stored key just as for any other non end to end encrypted data.