Short answer - use Fastlane to distribute via Testflight. Long answer - We had an issue with the app on iOS 14.6. XCode Version 13.3 (13E113). When distributed via Fastlane to Firebase - the app works fine. Running the app from Xcode works fine too. But when we distributed via Testflight using Xcode - app crashes at launch. No crash logs. I tried including libswift_Concurrency.tbd, disabling bitcode etc. Nothing helped. Finally I tried fastlane and it works! So yeah I assume there is some bug in exporting from archive in Xcode.