It's pretty simple. Tesla stock was (and IMO still is) overvalued. Part of that was some people seeing Musk as a kind of genius. His moves at Twitter are getting Tesla stock owners to reevaluate.
On top of that, the man is politically polarizing and the areas Teslas sell best in are *not* Trumpey bastions of 'radical free speech' (which I take to mean 'speech without consequences', but I'm one of those 'libtards' they despise).