I'm genuinely surprised by this. I figured the differences between tablets and phones, combined with Apple's efforts to distinguish between 'iPadOS' and 'iOS', would be enough to get them a win on this point. If the shared app store is part of the problem I wonder if that makes it a liability for any new apple ecosystem to tie into the App Store, like Vision OS for example.
I mean, regulators aren't stupid; just because Apple rebranded iOS on iPads to 'iPadOS' a few years ago, presumably seeing the writing on the wall, you shouldn't expect the EC to go "oh, well, the company we're regulating _says_ it's a different thing, so it must be a different thing".