This isn't good advice for trying to show someone their messages aren't being sent in clear text. It could be encrypted using a weak cipher or have other implementation bugs that make it trivial for a nation state to decrypt it. You need to be able to look at the application's source code to tell what encryption it's using and if it's secure enough.
Sure they can encrypt E2E but they don't. Most chats on Telegram are unencrypted. Huge channels like the one mentioned above are full of agents and nothing prevents them from taking screenshots.
Don't spread false security.
Maybe I'm stupid for not realizing or looking it up before chosing Telegram. Luckily there are a lot of other apps out there in the same space that do this better. Have switched to Signal now and really like it! Privacy should never be an opt-in feature like in Telegram!
So that would include world famous professional cryptographers like Bruce Schneier and Matt Green. Meanwhile the people recommending Telegram are random usernames on internet forums. It sounds like you're the only one who doesn't know what they're talking about.
"Anyone can start a private chat encrypted end-to-end"
This is such a shill talking point. Telegram doesn't even support E2EE for groups. Every dissident groups leaks 100% of its chats to server with no possibility to opt-out.