It’s encrypted in your phone, and in the receiver’s phone => both ends are encrypted => end-to-end encryption…They conveniently don’t say what’s happening between the ends though.
They actually do. They have a whitepaper, and it’s just the signal protocol as expected.
End to end is good, apps using it is good. The snark about apps using well known open protocols isn’t needed.
Talk about what the app is going to be doing with your data that isn’t transmitted, you can be snarky about that. But being like this about the use of the signal protocol isn’t helpful.