> Messages are still encrypted between client and server.

This is just a clever way of saying they use TLS, which I would be shocked if any mainstream app is not using.

Don't look under the hood at sms then

SMS is never claiming to be E2E nor is any army of SMS defenders online talking about how some virtue of SMS is almost same as E2E. While I don't like Telegram I will happily admit it is better than SMS, but how is that an argument for anything.

SMS isn't an app, it's a protocol that was created in 1992.

Ok so theyre plaintext on the server, encrypted in transit just means https

Is the server -> FSB connection encrypted?