The documentation text you quoted said it 100%—it's up to you to implement a mechanism to validate user purchases in any participating app. When there is an active subscription, from any app, you are able to unlock entitlements in all of the apps. When the subscription expires, you are also able to present purchase options in any app, too. Apple implied that you should have a back-end server at the minimum to implement subscription. There are services such as RevenueCat that takes away back-end server programming from you, so you may want to take a look at that.

I had the same error and fixed it. The cause on my project was that I accidentally called performChangesAndWait inside another performChanges (the latter is for creating a photo; the former is for creating an album to add the new photo to). Once I un-nest the call blocks they work fine.

Seeing the same using Xcode RC and the release version of iOS 16. All built using the Release settings. On top of the timer not counting down, the Text view element seems to take up any horizontal space that it can. Center alignment in VStacks no longer work as a result. Filed a bug report and hopefully this gets fixed soon.