This is probably the biggest component. It's slang. It started as a euphemism that turned into an in-group signifier. Same thing with other euphemism fashions. E.g. if you're up to date on the latest politically correct phrases, or the latest brainrot like "six-seven" or the latest prison slang, or the latest whatnot, it signifies where you spend your time, who you listen to, what social circle and status you belong to etc.
That said, the existence of taboos are a social universal. Some things are better discussed in some contexts than others, more intimately or more publicly etc. However, the 20th century zeitgeist has decided that subverting all taboos will be liberating, the personal should be political and vice versa, everything should stripped of context and dusty old rules, so now that we have the tech, let's just have short videos floating out there and sliding into people's feeds, talking about the heaviest subjects etc.
But then if tiktok suddenly pushed suicide content, and then someone actually committed suicide, and the two could be juxtaposed into a story, it would be a big PR issue. There is a reason companies don't want to go near these topics. Because then they have to police it by content valence. You can talk about heavy topic X from such and such angles, but you must list such and such caveats but also you are free to express your experiences with your own unique voice, lest those get "erased" or whatnot. We will need superintelligent AI to be able to satisfy all the contradictory expectations. Until then, someone will always grumble.