Almost three years ago, New York City joined governments across the country to ban TikTok from its phones over security concerns about the Chinese social media site. On Tuesday, Mayor Zohran Mamdani , a bona fide social media star, took to the app to announce a reversal: “TikTok, we’re back.” The city will now allow agencies to start posting again on the short-form social media site as long as departments follow a set of security precautions, according to a memo from city cybersecurity