It is likely that discord still uses 'old' VoIP notifications that worked well before iOS 12/13 dropped the hammer on them and forced developers to always show

It is likely that discord still uses 'old' VoIP notifications that worked well before iOS 12/13 dropped the hammer on them and forced developers to always show callkit on every voip notification. With those notifications, it wasn't really a problem, but apple killed them because some developers (Facebook?) abused them to gather location and other data.