BEIJING — China’s top leader, Xi Jinping, seemed indomitable when lawmakers abolished a term limit on his power early this year. But months later, China has been struck by economic headwinds, a vaccine scandal and trade battles with Washington, emboldening critics in Beijing who are questioning Mr. Xi’s sweeping control.

Censorship and punishment have muted dissent in China since Mr. Xi came to power. So Xu Zhangrun, a law professor at Tsinghua University in Beijing, took a big risk last week when he delivered the fiercest denunciation yet from a Chinese academic of Mr. Xi’s hard-line policies, revival of Communist orthodoxies and adulatory propaganda image.

“People nationwide, including the entire bureaucratic elite, feel once more lost in uncertainty about the direction of the country and about their own personal security, and the rising anxiety has spread into a degree of panic throughout society,” Professor Xu wrote in an essay that appeared on the website of Unirule Institute of Economics, an independent think tank in Beijing that was recently forced out of its office.

“It’s very bold,” Jiang Hao, a researcher at the institute, said in an interview. “Many intellectuals might be thinking the same, but they don’t dare speak out.”