No, there shouldn't be a law, unless you intend to outlaw in-app advertising entirely, which will make a lot of people sad that there are no free smartphone games anymore, but okay.
Oh no, not the scammy casino games targeting children with advertising. What will we do without them? Some people might even be able to charge money for games without advertising instead!
So the only games left would be worth paying for? Sounds good. Let’s get started.