latest update on this issue. I went to Apple Service centre this afternoon, they have checked my iphone and it is confirmed that the problem is something to do with hardware issue-Network Circuit Power Failure. This issue is common for Iphone 11 series. The repairing process is a bit tedious since it require stereo microscope, and infrared cam. You may check out the real problem through this Malaysian youtuber video. https://youtu.be/R6WplRELd1Q In my country, Apple don’t offer this type of phone repair, they only offer you one to one exchange with the new unit but you have to pay if it is not under warranty, bur if still under warranty (1 year), probably it cost you nothing. If in your country you can find out the certified technician to do this, it is worth a try.

Just updated to ios 15.1, the problem still persist