Probably a combination of:
Users flagging the post
Domain-based downweight (dang has mentioned it exists for Wikipedia for example, no idea if it’s automated or manual)
Posts with bad comments:upvote ratio get downweighted (IIRC dang calls them overheated discursions?)
And FWIW it’s on the front page now
[EDIT] no it’s not. I was on the new page not front haha. Probably people sick of hearing about Twitter and flagging then.