I have many comments about Telegram and how not-so-secure it is. Again, it does not have E2EE on desktop.[1] This secret chat is only for 1 on 1 conversations (IIRC), and it is not the default. I cannot comment on their E2EE because they may have changed it by now.

Telegram is fancy, it is a great replacement for WhatsApp, but it cannot replace Element, Conversations/Gajim (XMPP), Briar, Ricochet, or Wire. Please avoid Telegram for actually "secure chats".

I recommend checking out https://secushare.org/comparison. I disagree with "Telegram can be among the least worse [for smartphones]" though. It is Briar. I have also used Briar on desktop, I wonder where that will go.

[1] https://tsf.telegram.org/manuals/e2ee-simple#2-why-are-there...