I think it's worse than that: Apple managed to wrangle it so the new rules apply specifically to iPhone, and not iPad [1]. So the new rules apply only to iPhone devices in the EU. So then there's the absurd situation that, say, a Firefox user in the EU using the Firefox browser on both iPhone and iPad will in fact be using two entirely different browser engines. Imagine what a burden on support that will be, having to answer questions like "why do websites look/work differently between iPhone and iPad when I'm using Firefox on both?"

[1] https://9to5mac.com/2024/01/26/ios-17-app-stores-and-more-ip...