I had a long list before that, off the top of my head:
- notifications were broken (disappearing or not appearing at all) which included DMs, or appearing late
- the follow/unfollow problem that so many complain(ed) about
- the algorithm dominating the main feed (the For you and Following is at least an improvement on this, if not a fix). Not really a Twitter only problem that one.
- lists was the old fix for the main feed problem, but they would go missing at times and set up was a pain
- clicking on "More replies" (or whatever it is/was) and they disappear/don't appear, sometimes on tweets I've already seen
- Let's not forget when they last killed off 3rd party apps en masse[1]
- changing settings often wouldn't work, and are still a UI mess today
Related to the freedom of speech thing because the ways it was implemented lead directly to them:
- shadow banning (I hate that everywhere, including the hellban here). Even searching a particular account was blocked, which is a pain when you're trying to find something you know exists.
- watching stats drop precipitously on tweets after Twitter had put their thumb on the scale. Shouting into the void isn't a fun experience. Watching interesting accounts wither also was a waste. Still plenty of trolls and bots though.
- trending topics being curated. Possibly Twitter's real USP is instant news, the trends can give an idea of what people are really talking about at a glance and get you straight into breaking news. Most of that was gone. They're worth a look again.
And several forgotten problems, I'm certain of it, I could've spent all day going through them, at the time. What a pile of steaming rubbish!
I often wondered if the first half of this list should go under the second half of this list because most of them appeared after Twitter became blatant in its ways, and some of them occur on other social networks too, but only on contentious topics (it amazes me how little is said about the heavy censorship Facebook engages in, must have a better PR department than Twitter. Maybe that's why Musk fired them all).
Then you find you can't log in often or at all. When I saw that Project Veritas video about Twitter, I believed it, because it made sense that no one was doing any real work.