Unlocked s21 Ultra showing as "Unknown Device" and not supporting 5G or Extended Range LTE on My Mobile account

Voidyourwarranty wrote:

This is not a manufacturing problem or a samsung problem its a t-mobile problem.  If you can look up your own imei number and get the model, so can t-mobile.  They just don't do it. Why they don't I can't comment on but be sure it would take about 60 seconds to manually look up your imei number and if they had someone put in a couple hours of work they could build the automation in easily so I have to believe its intentional.

Probably because it serves no purpose!  Whether your device shows up as what it is or an unknown device has absolutely zero impact on whether your device works or not with the service.