Elon Musk's rebranding of Twitter to 'X' was chaotic and comical, as he failed to make basic preparations. Despite his long obsession with the letter 'X', it seems that nobody at Twitter checked if the trademark was already registered. It turns out that Mark Zuckerberg and Microsoft already hold the trademark.
https://kipcurriercopyright.blogspot.com/2023/07/elon-musk-apparently-didnt-bother-to.html
https://kipcurriercopyright.blogspot.com/2023/07/elon-musk-apparently-didnt-bother-to.html