@Meyerweb holy crap, have you seen the new App Store terms, though?
Even if your app is free, "Developers who achieve exceptional scale on iOS in the EU will pay a Core Technology Fee of €0.50 for each first annual install over one million in the past 12 months."
I would assume that is bad news for Firefox, who I hope have more than 1 million installs in the EU.
https://developer.apple.com/support/fee-calculator-for-apps-in-the-eu/