"If nothing, it breaks the retro atmosphere I'm going for"
I commented before about finding the ads annoying. But really, this is the crux of it. It completely breaks the experience, as I am playing a pixelized retro game and a modern looking clean ad appears on the screen.
Tangentially, why don't you consider also publishing the same game, but with a different art style. An art style that might be more relatable for kids these days (no idea which, just suggesting you research that).