They aren't pushing suicide videos specifically. Like most feed driven social media platforms, a video gets some engagement and it appears in the feeds of some users as a result. If it gets flagged or reported they take it down.
TikTok does actively take down content that violates their guidelines. Children are much more likely to come across nudity or porn on Twitter/Instagram.
Of course. I let "some users" do a bit too much work in my previous comment.
The point was that they're not doing anything that the other platforms aren't doing.
They seem to do a fair bit to identify content that breaks their guidelines. To the point that users often make up alternative terms for sensitive topics e.g. Nazis become Yahtzees/N@zi and suicide becomes unalive. The belief is that TikTok flags videos with these terms and may remove them outright or downrank them in the recommendation algorithm.
There's a lot more outright pornography on Twitter and Instagram than TikTok.
TikTok does actively take down content that violates their guidelines. Children are much more likely to come across nudity or porn on Twitter/Instagram.