It's called ghosted, shadow banned, too sensitive / shitshow; Basically a multiplier of 0.1 is added to this post's ranking, or similar, and it will need thousands of upvote instead of hundreds to show.

It's commonly applied silently to posts that simply don't look good or become a nightmare to manage the narrative of. It's a healthy way to manage a community while looking transparent.

I think it's sucky and cheap, but at the same time it's also the best solution.

If they do it, they should mark the post as such as give an explanation. Otherwise you never know if uncle "Sam" called and asked it to be treated as such.