Server-client encryption by default, not end-to-end encrypted by default. https://telegram.org/faq#q-so-how-do-you-encrypt-data

Yeah, with client-server encryption. Which doesn't matter at all. Encryption where the service provider has the key, which is the case for

* all Telegram chats by default

* all Telegram group chats

* all Telegram Win/Linux desktop chats

is indistinguishable from end-to-end encryption where the service provider has a backdoor (ANOM[1])

In both cases the service provider, and anyone who hacks them, can read your messages.

[1] https://www.pcmag.com/news/fbi-sold-criminals-fake-encrypted...

i don't think its e2e by default. I hope you are not talking about https.