In European nations who aren't English-first-language it's quite widespread around university students and people that outgrown Whatsapp, it isn't very much different than using a Discord groupchat (and you lose less important stuff in Telegram). Admittedly a bit is for network effect around "grindset" jocks but it isn't very much different than using discord or Meta messenger or Slack, just a freemium SaaS that the project doesn't support firsthand so if "our server" is down, "theirs" maybe is not. I say they are all the same although Telegram's insecurity is proven, they still are the same overall for a FOSS project.

It's not so much about security, as FOSS conversation groups would be open to anyone anyway, but it's not a good look for a project to use a tool that is known to be quite shady while there are FOSS tools, or simply tools with a better reputation. Also the project group seems to be french, not english-first-language, and Telegram is absolutely not well seen in France, not used by much more than a few percent

If you say "shady" because CEO is a Russian in Dubai and for years nobody really knew how the hell could he sustain the company, yeah you're right.

About the FOSS alternatives you're right, but to use a closed source SaaS is just a choice people make because they are not confident in their own infra.

If it's "shady" because of cybercriminals, I insist in saying that it's the same than using Discord (pedophile rings) or Whatsapp/Meta messenger (extensive history of terrorists, gangs, traffickers of any kind).

How is it shady?

It beats WA on UI in most cases (especially on desktop), has open source client, much better groups/channels for one-to-many, many-to-many communications. Has bots support like I never seen on WA.

Russians is a bit narrow, but it is mostly the popular choice in eastern Europe. But when it comes to these messengers it differs based on location. There is KakaoChat in Korea, WeChat in China, Whatsapp in central Europe and South America, iMessage in the US, etc.

That definitely depends on where you are. In Germany it's quite common, and in other countries too.

I use it over discord pretty frequently. The app UI is much simpler than discords and I've been able to get family to stick with using it because of that. Signal is my main way of communication, then telegram, then discord.

We used it as our family chat for many (10?) years. Only recently we moved to signal.

Discord is unprofessional and tiresome if you ask me; I regret that many projects I admire don't see it that way.

Nah, it is used by the likes of my 87yo mother who wouldn't recognise a crypto if it landed in a tree nearby and doesn't speak a word of Russian (she's Dutch). It is used by those who shun anything MetaFacebook and as such won't install Whatsapp. As such I have used it in the past but now mostly use my own XMPP server although I still have it installed on several devices to keep in touch with those who remain on the platform. I do know a few words of Russian but that is unrelated to my (mostly former) use of Telegram.

Furries use it too