Last October, Some Apple users reported that their iPhone 12 drops the cellular connection on 5G and 4G networks. This seems to be happening more often with Verizon and AT&T users but T-Mobile clients experience the issue too.
The owners of Apple iPhone 12 say that when they travel in a car then they face this problem. The workaround, for now, is to turn on the airplane mode on and off again. One of the commenters said that he was able to reach one of the PR execs. Also, he confirmed that Apple is aware of the issue and is currently investigating. Perhaps a fix is on its way.