I've tried to join multiple times over different Tor circuits. Each time I've been stopped by the "Give us your phone number" nonsense, but each time it has shown me the channel name and details, how many people are online, etc. I'm not familiar with Discord, but it seems like I actually join the channel and then am immediately asked to verify? That would perhaps explain my name showing up in the room.

I haven't ever yet got past the verification page, so if that's not the case, then yes, someone is impersonating me.