So far, you can still buy movies via itunes Movies and also see whether movies are available in 4K. This is supposed to disappear with the new central app for movies, series and so on. But it's complete crap. Regardless of whether I have Paramount+ or Disney+ installed or not, movies that are available on it first refer to the streaming service. I can then buy the movie from Apple, but the page shows me the technical data of the streaming service. So often only HD, although the movie is available in 4K on itunes. So I have to look on cheapcharts to see what's available for me. I don't want to be referred to the streaming services. I want to switch it off, but I can't. I love my Apple Tv, but the interface is getting worse and worse. And I still can't sort my purchased movies. Does Apple actually read the wishes of users?
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One option is you use CheapCharts, the apps quite good in that you can filter all 4K movies as well as the recently upgraded to 4K movies.
On top of that if you’re using the app you’ll receive a notification upon any price drops.
https://www.cheapcharts.info