• Uses a lot of stolen assets without giving credit. As far as I know, it still has many stolen assets in the game.
• A major, unavoidable mechanic of the game involves you crawling around on the ground and taking secret upskirt pictures of your underage classmates
• Game has made almost zero developmental progress despite being something like 10 years old at this point. It is widely accepted that the developer is likely intentionally dragging out the development time so that he can farm more money from his supporters
• Recently, it came out that the developer, a 30+ year old man, was having explicit and sexual conversations with an underaged girl. The texts (which were released online) show that he believes having sexual relations with a minor is "95% ok" (paraphrasing here). It also shows that he manipulated and gaslit her into keeping quiet about the relationship by accusing her of manipulating him. These texts were confirmed to be true and accurate by the developer himself in a YouTube apology video, although he never takes responsibility for his actions, instead claiming that the texts were taken out of context.

Those are the ones that I remember off the top of my head. There's more. Way more. And that's looking at only the legally questionable controversies surrounding the game. There's also a ton of moral and critical controversies