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.
"We are issuing a refund for all players who purchased any Save the World Founder's or Starter Packs (including Upgrades) and played Save the World on macOS between September 17, 2019, and September 17, 2020," the announcement reads. "Additionally, any purchased V-Bucks spent on Llamas on macOS in this period will also be refunded. As of today, September 17, 2020, Save the World Starter Packs will no longer be available for purchase on macOS."
Players do not need to request their refund. Epic will automatically credit their bank accounts, but it might take until October 2, 2020, to see the funds returned. Any V-bucks or items purchased or earned on players' accounts will not be lost. If users wish to continue playing on PC, PlayStation 4, or any other platform, all of their stuff will still be there, "thanks to cross-progression."
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.