I've been around much longer and things are always changing. What I've seen, probably in the timeframe since COVID, is that people used to drop a comment and rarely revisit any of the children comments. The child comments used to be mostly positive and potentially additive if only a pat on the back. Now, more so than before, I see the top level commenter coming back to defend themselves in GGP level comments. The children to their comment is likely to point out something they missed, why they disagree, point out broken functionality, critique or otherwise add a hint of negativity to the comments.

There's two parts. 1) the negativity is increasing a bit 2) the commenter came back and chose to defend/counter themselves. #1 alone typically has sorted itself out in the past, negativity got downvoted fairly heavy to the point where I think folks probably self censored themselves. The community and mods have managed this type of thing fairly well. The #2 part seems to me a relatively recent development. I'd blame it on the WFH flexibility giving everyone more real-time usage of the site and that facilitates debate/arguments.

That's my totally made up hypothesis on this. I still don't think I'd characterize the level of discourse as problematic. The fact we're discussing politics and world topics more often as a community it's natural for us to disagree more.