Ask HN: Why about a third of the submissions become dead in mere minutes?

If you check the newest submissions right now (https://news.ycombinator.com/newest), ten out of 30 are already dead, some only sent five minutes ago. On the second page, it's 9. On the third, 11. It seems unlikely that many people are downvoting them so quickly, and for most I can't see why they should be dead. I know that there's websites known to publish only AI slop which are probably blacklisted here, but it seems unlikely that a third of the submissions are about them. There's some automatic AI filter now? How does it work, and are people assumed to check all recent dead posts and vouch for them if they don't deserve to be dead? I imagine that the wide majority of users assume there's a good reason for something to be dead, and ignore it rather than performing that check.