The rank of the post got affected by the flamewar detector, not because of voting abnormality.
Please don't break the HN guidelines by insinuating this kind of thing without evidence—they're quite explicit about that (https://news.ycombinator.com/newsguidelines.html), for good reason because most such insinuations are just pure perception. The internet is a bit Rohrshcach diagram that way.
If you're worried about vote manipulation, that doesn't mean you should do nothing! But what you should do is email hn@ycombinator.com so we can investigate. We always do.
Your post got like 30 upvotes in 30 minutes (paid for) which made it rocket up to the front page. The HN mod team then manually removed it from the front page due to vote manipulation. Notice how after your paid votes ran out nobody else gave it many more additional votes - still hovering around 30.
Please don't break the HN guidelines by insinuating this kind of thing without evidence—they're quite explicit about that (https://news.ycombinator.com/newsguidelines.html), for good reason because most such insinuations are just pure perception. The internet is a bit Rohrshcach diagram that way.
If you're worried about vote manipulation, that doesn't mean you should do nothing! But what you should do is email hn@ycombinator.com so we can investigate. We always do.