Like most large social media sites, pre-Musk Twitter had some combination of algorithms and bureaucracy that act as a chaos monkey to shadowban and suspend accounts apparently at random, often with an inability to comprehend satire or under incoherent or undisclosed pretexts. The site's users and staff were predominantly left-leaning, so right-leaning accounts were disproportionately the victims of these false positives because of human bias in which posts are flagged and how they're subsequently moderated.
Musk bought the site under a claim of doing something about the bias after Twitter suspended the account of a right-leaning satire site. Many of the existing users were displeased by this, because they liked having a site whose moderation system was biased in their favor, so some of them left. Meanwhile new right-leaning accounts were created as you might expect. This affected the ideological balance of the site, so even though it's still somewhat left-leaning it's less than before. And now when the drunk chaos monkey suspends an account on the left, people are finding new satisfaction in their ability to blame Musk in particular.
Musk has personally bragged about banning a lot of left-leaning accounts and unbanning right-leaning. What is your evidence that the site still leans left?
Bans in either direction are only a small percentage of accounts. People with large followings have a large disincentive to leave (have to start over), and new users haven't had long to build followings, so most large accounts are the same ones they were before he bought the company.
Musk is not actually a right-wing figure -- he smokes pot, makes electric cars, isn't religious, etc. But he isn't a left-wing figure either, which confuses people who can't contemplate that the same person could simultaneously e.g. support gay marriage and think peculiar pronouns are silly.
The result is that he's more inclined to ban accounts he doesn't like, but what he doesn't like isn't inherently associated with any particular party. And if you look at the "left-leaning" accounts he's suspended, it's the likes of Aaron Rupar and Taylor Lorenz, who... well, here it is:
Musk bought the site under a claim of doing something about the bias after Twitter suspended the account of a right-leaning satire site. Many of the existing users were displeased by this, because they liked having a site whose moderation system was biased in their favor, so some of them left. Meanwhile new right-leaning accounts were created as you might expect. This affected the ideological balance of the site, so even though it's still somewhat left-leaning it's less than before. And now when the drunk chaos monkey suspends an account on the left, people are finding new satisfaction in their ability to blame Musk in particular.