Ask HN: What Happened to HN Recently?

At first, I myself noticed various comments from "greens", where they simply advertise some portal, but it was more and more of this. literally on every thread from the main list of HN.

And from time to time it even showed that the HN service was temporarily unavailable, so they literally took down HN.

But is there any official post about this event? I've been on HN for years and I've never experienced such a thing.