Fortnite was too blatant with it by doing this with all accounts including ones that had entered young ages but that doesn't mean other apps that follow the entered age are accurate it just means they aren't likely to get fined. Which sure - still fine Fortnite. Knowingly breaking a law because you want to doesn't make you exempt from the law even if the law is useless in practice.
I'd personally like if the law could be made into something more meaningfully verifiable I just don't think there is a reasonable way to do so. E.g. the UK has an opt-in requirement at the ISP level for porn access because "I am 18+" buttons weren't actually doing anything but making a legal bypass. Yet it's both a ridiculously bad solution and still easily worked around anyways.
https://www.superawesome.com/