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/
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)