Discord's new update has added a setting that allows people with your phone number in their contacts to add you automatically (thus outing you to acquaintances and colleagues)
AND some people are reporting this was enabled for them by default (unclear why; I cannot repro this in my own testing)
AND it uses the same account-level phone number as is used for verification and SMS 2FA, so you cannot just remove your number
absolutely god tier s-rank copper-bottomed shithousery. if users give you phone numbers so they can be safer when using your service, you must NOT then use those numbers for growth hacking. this is basic stuff. ffs.
strongly urge you to go to Settings -> Privacy & Safety and turn off all three boxes below, if any are ticked
also revoke the contacts permission from the Discord app in your phone's main Settings app