Maybe reporting this problem to Apple could help with an official answer.
I had problems with iOS 14.2 Beta 2 on real devices but not on simulator. I was able to fix it for me by setting automaticallyWaitsToMinimizeStalling = YES
With NO
i run into
Error Domain=AVFoundationErrorDomain Code=-11819 "Cannot Complete Action" UserInfo={NSLocalizedRecoverySuggestion=Try again later., NSLocalizedDescription=Cannot Complete Action, NSUnderlyingError=0x280e34d80 {Error Domain=NSOSStatusErrorDomain Code=-17221 "(null)"}}