I wanted to take an old iPhone 11 Pro and downgrade from iOS 18 beta to iOS 17 for testing. I can download today (Sept 26) the restore image for the iPhone 11 Pro (and many others) but when I try to restore it (Finder Option click, select restore image), Apple rejects it (I guess they won't sign it).
If find this to be a problem. There is no reason why an iPhone in developer mode can't be used for testing a release less than a few weeks after the next release comes out.
Why do they have the restore images if you can't use them? Why is there no restore images for iOS 17.7?