Twitter culture (depending on what parts of twitter you were on) was really hard to explain. Unless you used it and really knew how to, you don't really get the benefit from it. Its feed structure combine with post length and algorith meant that it was really easy for you to know what other people were saying about things going on right now (reality shows, football matches etc). It also made searching for news so easy (due to its Trending feature), so you were kept in the loop about things.
The meme culture of Twitter was also very unique. I can say with absolute confidence that Twitter memes were bomb (before Musk ruined it). Way better than any memes I'd come across on Reddit or Lemmy so far.
The only problem is you had to take Twitter in small doses. Stan culture and cyber-bullying culture were real negatives of Twitter. Certain people on that app were unhinged and that went unchecked because of how echo-chambers were set by the algorithm. You really had to check yoursel to make sure you weren't being corrupted, especially because cyber-bullying was so normalised there (at least in my experience).
I was under the impression not much had changed because a small minority used 3rd party apps tbh.