Twitter has changed its official handle from @Twitter to @X. If you attempt to access @Twitter, it now states: "This account is no longer active. Follow @X for updates." All past @Twitter tweets, (or X's, or whatever they're now called), are henceforth available in the @X account.
That's not all. The Twitter Blue subscription service is now called @XBlue (Blue subscription) in the main description page. That means the majority of older official Twitter handles have dumped the Twitter name or replaced it with X. For instance, @TwitterSupport, @TwitterDev and @TwitterAPI are now @Support, @Xdevelopers, and @API.