For those who are interested here is a solution: https://stackoverflow.com/questions/68835388/i-cant-add-systemextralarge-family-in-widgetconfiguration-for-ios-15

Hi! I have run into the same problem of including if #available(iOS 15, *) in the WidgetConfiguration. Have you found a solution?

The problem has already been resolved.

In Signing & Capabilities I use a different package identifier than iOS. I have done a test exporting the app with the same identifier as in iOS and iCloud has worked. But I need my app to keep the bundle identifier different from iOS in order to continue supporting my users.

I have the same problem. I will also send a bug report.

Hours later the same problem continued. I decided to submit the app for review again.