https://techcrunch.com/2023/04/11/twitter-inc-is-now-x-corp/

Twitter, Inc. is now called X Corp, according to a court filing in California.

Since Twitter is no longer a public company, it does not have to report updates like name changes to the SEC. But in any case, the new name was spotted in an April 4 document related to far-right activist Laura Loomer’s lawsuit against Twitter and Facebook.