Many in the crypto and privacy community mistakenly trust Telegram because it’s “end to end encrypted”, but there are huge issues including not hiding the metadata, censorship, centralization, and phone numbers.
Send this video to your friend that asks why you won’t join:
https://video.simplifiedprivacy.com/why-telegram-sucks/
Who thinks in the privacy community that Telegram is end to end encrypted? They were largely mislead. That’s an option, that even prevents sync of the chat between your devices.
The thing is, Telegram has some shady things, but until Matrix becomes usable this is one of the very few usable options. And until then, use Telegram FOSS from F-droid.
How is matrix not usable?
Fortunately they are working on all of these, and as I just found out recently, they also have an alpha version app now that makes use of the new efficient sync, which I expect to fix 2 of the above (the resource usage is partly because of how sync works now)