https://arstechnica.com/gadgets/2020/08/apple-wont-let-stadia-or-xcloud-into-ios-citing-app-store-guidelines/

Cloud gaming is increasingly becoming a thing, one that lets you play AAA games on a device regardless of the hardware specs. If your device can stream a video, it can probably play Red Dead Redemption on Google Stadia or Halo on Microsoft's xCloud (which is now technically called "Cloud gaming (Beta) with Xbox Game Pass Ultimate"). If your device is an iPhone or iPad, though, you're out of luck. Apple says these apps violate its App Store policies and will not be allowed into Apple's walled garden.

Apple sent a statement to Business Insider: