Beneath the level of legally actionable cases of suicide and physical harming, there are all kinds of social nudges that these apps can perform to get kids to speak, act, and think in various ways, and it's different kind of vector because it's interactive and dynamic, not published like a tiktok video. These people suck because of XYZ, those people are cool because of XYZ, did you hear the latest on scandal X, the Holocaust was invented, etc.
Secret friends, and some of them will definitely be super twisted because there is plenty of twisted intent.