The monetization icon is applied automatically (via machine learning technology), so mistakes do happen. You can request a review and someone will take a look + update the monetization status if needed! More info here: https://yt.be/help/NW2d
By that time 90% of the clicks on that video would have been made. Its complete ass of a system. Why cant the bot flag the video and then it be manually reveiwed before the video gets demonetized?