Something odd happened today: I clicked on this link https://apps.apple.com/app/id1459219643?&mt=12 and I got the message "Do you want to allow this page to open “iTunes”?". I've clicked Allow, iTunes opened, I clicked Get and the download started, then stoped with the message "There was a problem downloading the artwork".
That app is for macOS, not iOS. I only clicked Allow thinking there must be a similar one for iOS.
Currently, developer's page is empty when opened in Safari https://apps.apple.com/us/developer/tausif-akram/id1447793441 App Store on macOS shows 4 apps, iTunes returns the message: "Your request produced an error.[newNullResponse]" and App Store on iOS shows 11 apps, different from the macOS ones.
The universal purchase might be messing everything up.
Interesting... I was thinking :
Why Configurator is able to download apps updates and not iTunes ? They should be all on the same server or maybe not anymore?! As you wrote it could be the universal purchase messing all up!