Filipe Espósito, 9to5Mac:

Apple today released iOS 14.7 beta 2 for developers, and while bugs and other weird issues are quite common in beta software, sometimes they can make your device nearly unusable. According to some reports, today’s beta seems to be causing a “SIM Failure” error for iPhone users.

Not enough data to know for sure, but this may be an eSim issue. But that said, if you’ve not yet made the leap, I’d hold off on installing the latest beta until this gets sorted.