I don't think this is some big gotcha - this has always been clear.
Seems like there's just one rule they don't like, that it's EU only. Which is fair enough.
Personally, I don't see why this is the hill Apple's dying on. They seem to have put in a fair amount of effort into creating a problem and APIs to allow for other browser engines to exist as peers to Safari (allowing JIT, multi-process, hooks into Lockdown Mode etc), but then restricted that all to the EU. This one seems more ideological than financial (like the other DMA-forced additions Apple is doing).
But really - its not really clear to me what benefits users get from this. Safari (on iOS or Mac) hasn't stagnated and is a highly performing browser, better than Chrome and Firefox in some regards. It supports some APIs first that others lag on, while it lags on others. I am a web developer, and I really do not agree with any claims that Safari is somehow worse than other browsers.
Meanwhile, people are shipping 'new web browsers', that users seem to like, by using the webkit engine under the hood. UI, features, sync, etc are what actually matters to users.