iPhone 12 mini NO SERVICE or SEARCHING and blank mobile settings page (empty when tapped under Settings)

On iOS 14.6; randomly and also when phone is restarted sometimes I get no service, or the phone is stuck searching for service forever.

Before some iGenius gives the standard try this answer, I've done all of that.

SIM works in other phones, other SIM cards also don't work in my phone. Resetting Network settings doesn't work. Restarting phone doesn't work. Turning on and off Airplane mode doesn't work. Cleaning the SIM tray doesn't work. Update from carrier is not available, the carrier did everything they could when I called them, as well. The only thing that works is restoring the phone completely. I have to back it up and then fully restore it every time. This is insane. Is it hardware? Seems buggy and sporadic enough not to be. And why is the mobile settings page blank every time this happens?! This started happening on one of the previous 14.x OS versions, so it's not just 14.6.

This happened on older iPhones, I see reports from 2016, 2017, 2018 etc. Some iPhone 7 units were recalled over this. (https://support.apple.com/iphone-7-no-service)

[Edited by Moderator]