I have noticed this stopped working recently. I think iOS 18. My solution is to provide a link that the app can handle and then to create a small landing page in case the user is not redirected.

I think Frazil is trying to diagnose an issue in their app via the Apple-provided reports in the Organizer window, but is getting an error ("Please provide a valid value."). I have been having the same issue: https://forums.developer.apple.com/forums/thread/767331

Thank you Ed. I have submitted FB15661357.

Yes, window.open is still working for me (iOS 15 and 15.0.1)