See https://en.wikipedia.org/wiki/Blank_piece_of_paper and https://en.wikipedia.org/wiki/2022_COVID-19_protests_in_China and https://zh.wikipedia.org/wiki/白紙運動 (Chinese article specifically about the blank paper protest)
Some in China believe that the "A4" (as in A4 paper) protest (Nov 26, 2022) was the main reason that covid restrictions were lifted on Dec 7, 2022, or helped accelerate the process. I for one don't believe this as restrictions were already loosening since Nov 11, 2022.
~~Most~~ All of the information is from foreign sources because of censorship around such topics in authoritarian China, but you have to question their authenticity because protests are banned in China.