From the Epic Games Blog:

We recently announced that Apple approved our Epic Games Sweden AB developer account. We intended to use that account to bring the Epic Games Store and Fortnite to iOS devices in Europe thanks to the Digital Markets Act (DMA). To our surprise, Apple has terminated that account and now we cannot develop the Epic Games Store for iOS. This is a serious violation of the DMA and shows Apple has no intention of allowing true competition on iOS devices.

[...]

In terminating Epic’s developer account, Apple is taking out one of the largest potential competitors to the Apple App Store. They are undermining our ability to be a viable competitor and they are showing other developers what happens when you try to compete with Apple or are critical of their unfair practices.

If Apple maintains its power to kick a third party marketplace off iOS at its sole discretion, no reasonable developer would be willing to utilize a third party app store, because they could be permanently separated from their audience at any time.

UPDATE, Epic Games CEO Tim Sweeney says its developer account was reinstated following “a swift inquiry” from the European Commission:

March 8, 2024 Update:

Apple has told us and committed to the European Commission that they will reinstate our developer account. This sends a strong signal to developers that the European Commission will act swiftly to enforce the Digital Markets Act and hold gatekeepers accountable. We are moving forward as planned to launch the Epic Games Store and bring Fortnite back to iOS in Europe. Onward!