Epic Games' wildly popular multiplayer shooter game "Fortnite" is available again on Apple's app store in the U.S.

The problem is that Apple is specifically not allowed to “prohibit” the use of external payment links. It can reject apps, or ban developer accounts, at its own discretion. But if it rejects an app or bans a dev for no reason other than its use of such links, does that amount to a de facto prohibition? Again, that’s debatable.