What I think has happened is that the culture wars are taking over more and more topics. Not only the obvious stuff like race, LGBTQ+ rights, crime, and labor, but increasingly things that don't traditionally fall on the left/right axis: vaccines, lab leak theory, content moderation, and even programming languages to some extent (admit it, the representation of trans people in the Rust community triggers some people).
One thing that gets me is that, putting aside the question about whether one side or the other is right, the culture war stuff is just incredibly stupid. It's like people have gotten a lobotomy and their ability to do critical reasoning and respond to empirical data has been replaced with just pure tribal identity. My sense is that this is happening across the country (and perhaps to some extent the world), and HN actually has it easier than a lot of other places.