Swift forum thread reports crashes on iOS 14 trying to use Swift concurrency features. According to forum thread this issue is not reproducible in Xcode 13.1 or in new Xcode beta. Crash could occur on both release and debug builds.
Moreover, crash is NOT reproducible when running app through Xcode, or via TestFlight distribution. Also, crash is not reproduced on Simulator both on Intel and Apple Silicon Macs.
Other Apple platforms might also be affected, additional verification is needed.
Issue is related to back-deployment library which could also be replaced during build.
Overall, Swift concurrency features should be tested on all supported platforms.
Swift Forums: Async Await crash on iOS14 with Xcode 13.2.1
Developer:Try running apps in any configurations. Follow build workarounds for concurrency features, if needed.
QA engineer:Carefully test apps on all supported platforms on devices.
PM/DM:Beware of issues with Swift structured concurrency. Carefully add these features, if support for previous OS versions is required.