Telegram isn't remotely similar to Signal. Telegram communications aren't encrypted by default, and Telegram group chat messages aren't encrypted at all.
To say there's no encryption AT ALL when it's fully encrypted over the wire is still false. Not having E2E encryption is different than not having encryption AT ALL.
Group chats aren't end-to-end encrypted, and 1 on 1 chats are only end-to-end encrypted if you make it a Secret Chat.