General understanding is that the flamewar detector is triggered when posts exceed 20 comments and total comments exceeds votes:

<https://www.righto.com/2013/11/how-hacker-news-ranking-reall...>

It's not perfect, but it really does often correctly identify flamewars. If you feel a post has incorrectly triggered the flamewar detector, email mods at hn@ycombinator.com.

As I write, this thread doesn't trigger the criteria.