Twitter/X changed the TOS so that it's now impossible to opt out of having your posts used to train their in-house model "Grok". This caused an exodus of artists (and their followers).

The U.S. Presidential election and its outcome on November 5th was the inflection point for the significant migration from X to Bluesky, as a) many were staying on Twitter/X only for the real-time news and discussion about the election results which ended up not being that interesting due to the Trump sweep and b) the results in favor of Trump will give Elon more power and make Twitter/X more insufferable.