TL;DR: The latest casualty in Epic’s war with Apple is Fortnite: Save the World. The co-op PvE shooter is not getting pulled by Apple directly, but it needs an update to continue working cross-platform without bugs. This cannot happen because Apple terminated Epic’s developer accounts, so updates cannot be signed and made available to users.
Epic Games announced this week that it has to pull the plug on the macOS version of Fortnite: Save the World. Due to its ongoing legal dispute with Apple over the App Store tax, Apple revoked Fortnite developer accounts. Therefore, neither Fortnite: Save the World nor Fortnite: Battle Royale on any Apple platform can be updated.
The Fortnite Team says that the upcoming v14.20 rolling out to all other platforms causes bugs for players still on v13.40. Since it cannot sign updates to fix these issues, it will discontinue Save the World on macOS. Starting on Septemeber 23, 2020, the game will no longer be playable for Mac users. Players will be refunded, however.
Epic added that Fortnite: Battle Royale will remain playable on macOS for now since it does not have any updates slated that will cause problems. However, keep in mind, Fortnite BR still can not receive any bug fixes for Mac, and a future update to other platforms may render the game unplayable at some point.