They are for sale https://buygithub.com/product/stars/ so it is very suspicious in this case, when there is a sudden spike, a marketing blog mentioning them.

My personal experience is that most stars on my projects come from empty accounts that star random stuff to avoid getting detected when they star the projects that paid.

I read somewhere that "fake" stars get pruned pretty quickly.

Regardless, imperfect as it is, a GH project with 20k stars feels more credible than one with 200.

(I write this as someone who works full time on a GH repo with 200 stars! :D)