China knows very well that their sanctions mean nothing. They did it anyway for the narrative within the country.
https://www.reuters.com/article/us-usa-china-sanctions/biden-administration-calls-china-sanctions-on-trump-officials-unproductive-and-cynical-idUSKBN29Q09B
https://www.reuters.com/article/us-usa-china-sanctions/biden-administration-calls-china-sanctions-on-trump-officials-unproductive-and-cynical-idUSKBN29Q09B
U.S.
Biden administration calls China sanctions on Trump officials 'unproductive and cynical'
China's move to sanction former Trump administration officials was "unproductive and cynical", a spokeswoman for President Joe Biden's National Security Council said on Wednesday, urging Americans from both parties to condemn the move.