After Android 11 update volte is disabled.
Reset once phone. And check setting.
Is this for real...are you a Dev? This is technically switched off by the OOS. This is not a bug that you can solve by even hard reset.
I'm user. Like you. And i said as per my usage.
It's working well for me, so I'd say that you are spewing utter bull crap.
Try resetting your phone and learn to be courteous when someone tries to help you.
New Raffles : OnePlus Urban Traveler Backpack (Arctic White)
by Elyn Lu, 2021-09-18