Embeddeding advertisements in the products or services is one of the ways for the company to make money but the serious downside is that the advertisements may be used to track users illegally by collecting or even stealing data from them for some bullshit purposes. Maybe there should be an app that doesn't have the ads at all and that it should be free even if it is highly popular but without advertising your app, you won't be able to make money from it as a developer. Perhaps, there should be other ways in making money like DLCs, in-app purchases and that's that.
It may be unbelivable that YouTube Kids app is under FTC scrutiny for targeting ads at children. Why do you want to be brought to things by those ads? And the annoying thing about ads in YouTube or any other app is that there may be video ads that do or do not have relations to the apps/services at all and it can be extra annoying that you may have to watch the entire ad in order to proceed any further. I think that it may be the most annoying moment on YouTube unless you have the extensions that go against the ads which can be simple to get but for YouTube Kids app, I can probably assume that there are ads about stuffs that will affect the people in a negative way whether they are children or not. So if the ad is about Cola-Cola product, it's a negative example because there may be something unhealthy about soft drinks like Cola-Cola ones. Even worse is that the other channels children may want to watch thanks to those ads may require subscription from their parents.
Or better yet, there shouldn't be ads in the first place because illegal tracking by ads is one of the security bullshits and that you should stick on to something really healthy and decent online services.