Cool. Twitter has made this much more difficult, by (a) embracing a pay-for-attention model, where bluetick replies, which are rarely worth looking at, are artificially promoted and (b) by making mass-blocking far more difficult (through the death of the API). So, people are sensibly going to Bluesky, which provides a better product, with sensible, choosable reply prioritisation, and a first-party blocklist system.
Like a big part of what's going on here is that Twitter is a way worse product than it used to be, while on the other hand better competing products exist in a way that they did not before. It's pretty natural under those circumstances that people go from the bad product to the good product. This is, broadly, how most dead social networks have died, both those which actively made themselves worse (livejournal, Digg, Tumblr), and those which were merely overtaken (Friendster, Myspace, Slashdot).