I find these complaints bemusing. They’ve had since June. It’s not Apple’s fault if they wait until the last minute in the hope bugs are due of the betas and not their shoddy scripting. A week’s notice makes little difference, other than a guarantee that your app update is available on day 1. Bugs and crashes with your app should be ironed out by now and on the store before 14 ships. All you need yesterday’s Xcode update for was to simply to submit a version of your app that uses the iOS 14 specific APIs. If their app wasn’t ready to submit before this version of Xcode was made available, then that’s on them.
I have 3 apps on the store in active and ongoing development. Those are ready, and the versions with iOS 14 specific APIs were submitted this morning and approved, so we’re all good to go, with no known crashes or major bugs. I suspect a few issues will prop up, as they do every year once users update to the new iOS versions, but we’ll get those patched and updated too, as always. There’s no issue here, in my opinion.
there does exist an edge case where you’d have to be incredibly unlucky, in that the GM release completely bricked your app. In which case, not always the dev’s fault and I sympathise. But this can happen with any software update versions, of which no notice is ever given. This is part and parcel with building apps though. You just have to adapt, and delay if necessary.
We once had an issue back in iOS 12, where one of our apps was quite happily running just fine on a beta build, then Apple released a slightly update version of the beta to the public, and our app would no longer launch. Wasn’t much we could do other than to rush out a quick fix to submit ASAP to tide us over a few weeks.