I think all the social networks, not just ticktock, are trying to influence people in often a negative way morally. Its the parents responsibility to curb that influence, and not just with excluding them from the applications, but more importantly teaching them good morals actively, not just responding with teaching when they fail to live up to your moral standard. Those children wont always be under our protection, so we "must" teach them good morals, and teach them why those morals are important, and give examples of bad morals found in those applications. And teach them that hell is not the only bad result of bad morals (aka sin), but a great bad price is also being paid in our lives here on earth and how if we have bad morals, it not only affect ourselves negatively but those around us we care about.