While there aren't direct speech restrictions in platforms like YouTube, you're leaving out the crucial detail that mentioning words like "suicide" gets your video demonetized, which directly causes similar self-censorship.
YouTube pays creators based on advertising deals making some topics far more valuable, while other topics have become very sensitive to advertisers. That’s related, but different from censorship.
Creators are still free to use YouTube as a platform to discuss sensitive topics with a very large audience without paying per viewer, unlike say advertising or standing at a street corner talking to passersby. As such YouTube is still supporting the discussion and distribution of said content.
