[Apocryphon]

Yes, and they would be angry at the people who make their apps for doing that for no apparent reason, the users who are more tech savvy will recognize that this is a ploy to harvest their data by forcing migration to platforms with fewer privacy restrictions, there will be big public backlashes on social media, people will boycott these new app stores simply because of the hassle, the companies will be forced to reverse their decision and put their apps back onto the App Store, and it would be an expensive waste of time.

One can even imagine that if the app getting moved is sufficiently widely used and utility-like, such as WhatsApp or Messenger, or even Facebook itself, the courts might start antitrust investigation into Meta, and that company would face pressure to keep those apps available on both their own Facebook Store and on the official App Store (where the majority of users are). After all, antitrust provisions apply not only to Apple, but to all companies.