This order was also released recently:
Apple is permanently restrained and enjoined from prohibiting developers from including in their apps and their metadata buttons, external links, or other calls to action that direct customers to purchasing mechanisms, in addition to In-App Purchasing and communicating with customers through points of contact obtained voluntarily from customers through account registration within the app.The Verge
To sum it up, Apple is no longer allowed to prohibit developers from using third-party payment systems, which was the main reason why Fortnite was banned from the App Store in the first place. This is a pretty big deal for other game developers looking to have their games on iOS operating systems and making a good chunk of money from it. Epic CEO Tim Sweeney was not a fan of the new changes, however, claiming that the new rule still was not fair for game developers or consumers.
Fortnite has not returned to the App Store just yet, but Sweeney has mentioned that it will when both Apple and Epic payment systems can coexist at the same time.