My iPhone 8 Plus fall down along with charger while charging, and charger pin broke and got stuck in charging socket. After that phone started displaying "No Service" for VI SIM (India). I tried another provider Airtel SIM, but same issue. Phone was upgraded to 14.7.1 few days ago.
Occasionally network is displayed, but for most part of the day, it displays "No Service". I am not sure whether its 14.7.1 issue which could be fixed by update from Apple, or whether its hardware issue.
I had visited Apple Service Center, but they said hardware fix could cost from INR 5K to 15K depending upon which part needs to be replaced (IC or whole board). They did not had hardware available for iPhone 8 Plus and asked me to visit another Service Center.