This is the first time I’ve seen this after uploading to TestFlight.
I received this email:
App Store Connect
Dear Developer,
We identified one or more issues with a recent delivery for your app, “myAppName” 4.5 (2022.3.251745). Please correct the following issues, then upload again.
ITMS-90424: Invalid Swift Support - The SwiftSupport folder is empty. Rebuild your app using the current public (GM) version of Xcode and resubmit it.
Best regards,
The App Store Team
This problem has occurred with the latest build version 3666.
Thank you for letting us know. I created an issue to track the progress:
Can you please post build.settings, Xcode Version, and iOS SDK Version
I’m using Xcode Version 13.2.1 (13C100).
Where can I find the iOS SDK version? After completing a build, the output does show a reference to this, “/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk”
I’ll send you the build.settings via Skype.
Usually this means you are missing the exact files it mentions. Last time I checked the FAN plug-in includes them. I know how you hate my workarounds.
Apparently, @vlads and @Scott_Harrison have found and fixed this error and I can now safely create my build. As Vlad explained, there was an issue with the ironSource plugin I’m using for Ads relating to a Facebook framework that has been resolved. Thanks to both of you guys 
Also, to fix the issue, I also had to upgrade to the latest Xcode 13.3