Telegram is not encrypted speech! The connection to telegram server is encrypted (with home baked cryptography - not a good idea especially in chat protocols), but the data is not end to end encrypted and Telegram servers see plaintext.

There is an option to do a sort of home cooked encrypted one on one chat that no one uses, but any groups/channels are just a goldmine for whichever intelligence agency gets their fingers on it.

If you want encrypted: signal, simplex, ...

Here's a comparison: 
https://juraj.bednar.io/en/blog-en/2022/05/03/encrypted-messengers-comparison/

Here's an explanation on why I think it matters: 
https://juraj.bednar.io/en/blog-en/2022/04/29/encrypted-messengers-how-to-communicate-privately/

Also: Nostr is also not encrypted.