https://wccftech.com/facebook-data-leak-shows-even-mark-zuckerberg-is-on-signal/

Facebook went through a massive data leak over the weekend where data of 533 million Facebook users was leaked, and guess what, Mark Zuckerberg's information was in it, too. This means that Zuckerberg's name, location, contact number, marriage details, Facebook ID, and other relevant information was leaked. However, we have now learned that his leaked phone number confirmed that the Facebook owner also uses Signal rather than Signal's biggest competitor WhatsApp, which Facebook also owns.

Dave Walker, a Cyber Doctoral Researcher, shared a tweet showing how even Zuckerberg is on Signal.