Maybe not but they have all the timing info, the identities of the chat participants, and the facebook surveillance network. They also used to leak URLs pasted into the app out in order to generate previews, so they know what you’re linking to from within the app. Us they can infer way more about you than seems obvious at first.
They are encrypted to your device and your device can upload them unencrypted in backups if you don't configure encryption. Plus the original argument was Meta did not have access.
