People in China’s southern manufacturing hub of Guangzhou clashed with white hazmat-suited riot police on Tuesday night, videos on social media showed, as frustration with stringent COVID-19 rules three years into the pandemic boiled over. The clashes marked an escalation from protests in the commercial hub of Shanghai, capital Beijing and other cities over the weekend in mainland China’s biggest wave of civil disobedience since President Xi Jinping took power a decade ago. In one video circulating on Twitter, dozens of riot police in all-white pandemic gear, holding shields over their heads, are seen advancing in formation over what appeared...