This fixed it for me, but only after quitting the Simulator after disabling all these settings.

I am suspicious that this is an Apple back-end problem yet Apple refuses to acknowledge it. Perhaps they are running a script or perform manual actions to fix game center support. Either way it is pathetic. This problem has been occuring for many years now and never is there any solution apart from "hey suddenly it works now!".

I will try that, I have also submitted a request to Apple Developer Support.

Exactly, last month I also added a new app and it worked fine in those good old days.

I did that too but did not help :(

My approved TestFlight build also doesn't work.

I ran my game again, still not working. Went to App Store Connect, deleted an achievement, and HEY PRESTO! It works now! This is definitely a bug in Apple's back end. Looks like it takes about five days and then it automagically works.

Yes and here, too after five days I deleted an achievement and tried again. Now "it just works".

This did the trick for me. I was afraid to delete the App ID (because my app was already in the app store AND it was transfered to another developer account). But I could uncheck the Game Center select box in the app identifier under "Certificates, Identifiers & Profiles". I had unchecked this box previously but it was auto-enabled again after trying to upload my build! Changing the bundle ID temporarily made it possible to uncheck Game Center and it would no longer be auto-enabled again.

Same here, AVAudioPlayer on iOS 17 simulators creates enormous lag to the point that apps stop running, but not on iOS 16 or on real devices.

Which JWT class are you using?

Thank you, preloading the players does in deed help, I have about 30 sounds plus music, so I'll look into the AVAudioEngine solution.