Videos had showed hundreds of workers marching at the world's biggest iPhone factory in the city of Zhengzhou, with complaints over Covid restrictions and claims of overdue pay.Last month, rising Covid cases saw the factory locked down, prompting some workers to break out and go home.Separately on Thursday, authorities ordered the city to go into lockdown, saying people would not be able to leave the area unless they had a negative Covid test - affecting more than six million people in the city.It came as China recorded its highest number of daily Covid cases since the pandemic began, with the country seeing a wave of outbreaks with several major cities like Beijing and Guangzhou affected."Although the zero-Covid strategy has become nimbler over time, the combination of more contagious Covid variants and persistent gaps in vaccinations have led to the need for more frequent lockdowns, weighing on consumption and private investment, including in housing," the IMF said."