Patently Apple have found out that Apple has patented a 5G Cloud Gaming service. This patent is about playing cloud gaming via subscription so in reality it would a competitor to xCloud and Stadia. This may one the reasons why xCloud and Stadia would not be allowed on the App Store.
With the recent Epic Games legal filing in regard to Fortnite, and the news of Apple blocking xCloud and Stadia, the timing of this would be inconvenient for Apple. While this patent does not mean Apple is entering the Cloud Gaming market it does mean they are at least looking at it. We will have more on this as we get it.