Interesting. I assumed Discord itself aggressively demands your phone number regardless of the “server” you join… At least, that’s been my experience.
That's the impression that is being given, but its not true.
I've been successful in a very few cases of getting a Discord server admin to dial back the verification level from 'highest' to 'high' on their server, so that I was not prompted for a phone number. They agreed that the highest setting was overkill.
Most times though server admins refuse to do so. Gotta wonder at this point if they actually see the phone numbers or not. Other server admins say they can't see the number, so will assume that's correct.