Especially when the reason for the move is obvious. If Facebook leaves the app store, and Facebook is completely free and makes money from advertising, everybody knows why they're doing it and it's to screw you out of your privacy. But you can't say no because Facebook is the only way you have to talk to your grandparents, hence the need for antitrust.
If Epic Games moves Fortnite to another store because the other store charges lower fees but still has a good reputation for not allowing bad apps, likewise the reason they moved is obvious. It's to have lower fees, because Fortnite makes money by selling things in the game. Many users will be fine with that, as well they should be, because that's the point of allowing other stores.
But a game doing it for the same reason as Facebook, well, they're going to lose most of their users. Because nobody needs a game that much, so the company doing it for an adversarial reason will cause large numbers of customers to tell them where to go.