I once visited Moscow for a AI coding jam sponsored by the Russian state, and while I was there, there was a Telegram group for all of the students to use to communicate during the jam. This Telegram channel was set up by the state officials.

A small section of Russian students were floored, and responded that they thought Telegram was banned in the country at the time (circa 2017-2018). The state officials laughed and responded that it wasn't any concern because they could read everything in any chat they wanted.

I've avoided the app ever since. I can't say how, why, or when the app became compromised, but anecdotally, I was told that it was and that it was no longer a concern in Russia.

Maybe it was some dry joke, maybe those students were woefully misinformed, who knows. But it certainly broke any confidence I had in the security of any existing messaging app.

I personally use Signal, but that's mostly just because I have personal friends who use it and it's convenient to use on my PC.

Edit: Kinda funny, I only just logged into this site again, and some of my last previous comments were about the same thing.