I've been lurking on LW for many years, and overall, my impression is that there's been steady progress. At the end of a very relevant essay from Scott, way back in 2014, he states:
I find this really exciting. It suggests there’s this path to be progressed down, that intellectual change isn’t just a random walk. Some people are further down the path than I am, and report there are actual places to get to that sound very exciting. And other people are around the same place I am, and still other people are lagging behind me. But when I look back at where we were five years ago, it’s so far back that none of us can even see it anymore, so far back that it’s not until I trawl the archives that realise how many things there used to be that we didn’t know.
5 years later, I still think that this still applies. It explains some of the rehashing of topics that were previously discussed. All the things I'm going to point out below are some of the most notable insights I can remember.
When LW was relatively inactive, there were essays from the surrounding sphere that stuck with me. For instance, this essay by paul chrisiano. Which was, for me, the first clear examples of how epistemically irrational things that humans do can actually be instrumentally rational in the right setting, something that wasn't really discussed much in the original sequences.
I think LW has also started focusing a fair bit on group rationality, along with norms and systems that foster it. That can be seen by looking at how the site has changed, along with all of the meta discussion that follows. I think that in pursuit of this, there's also been quite a bit of discussion about group dynamics. Most notable for me was Scott's Meditations on Moloch and Toxoplasma of rage. Group rationality looks like a very broad topic, and insightful discussion about it are still happening now. Such as this discussion on simulacra levels.
On the AI safety side, I feel like there's been an enormous amount of progress. Most notably for me was Stuart Armstrong's post: Humans can be assigned any values whatsoever.. Along with all the discussion about the pros and cons, of different methods of achieving alignment, such as AI Safety Via Debate, HCH, and Value Learning.
As for the sequences, I don't have any examples off the top of my head, but I think at least some of the quoted psychology results that were referenced failed to replicate during the replication crisis. But I can't remember too much else about them, since it's been so long since I read them. Many of the core idea feel like they've become background knowledge that I take for granted, even if I've forgotten their original source.