[forgotmypw17]

Here is a really fucked up Telegram mis-feature I discovered recently:

If Alice and Bob are in the same chat

and

Bob has Alice's number stored in their phone's contacts list

and

Bob refers to Alice in the chat (using @Alice)

then

Telegram will disclose to all the chat participants whatever name Bob has stored for Alice in their contacts (instead of the name Alice specified in their Telegram profile)

[Nemo_bis]

That's incorrect. Telegram shows what the user has sent, only that. The autocompletion depends on whether the mentioned user has chosen a username, and other factors.

[kayodelycaon]

This is why I got a cheap burner sim.

[wtn]

This is why I block mobile messenger apps from accessing my contacts.

[rideontime]

That doesn't help you if you're Alice.

[ignoramous]

You can vend burner numbers and don't need to own a sim per se. Check out apps like Numero eSIM.