China puts targeted sanctions on the State of California and Pelosi's donor network. They mimic US language of oligarchs and foreign interference repeated ad nauseum by US media and government. They outline her financial interest in Taiwan and abuse of power to become wealthy during her political career. The PR campaign and heavy sanctions work to politically isolate her from allies and neuter her influence, she's left out to pasture to "Spend more time with her grandchildren" shortly after the election where Democrats get obliterated.
The stupid imperialistic gesture finally ends the reign of one of the worst neo-liberal ghouls of a generation and China stays winning.
The scenario you outlined isn't realistic at all. No propaganda campaign the Chinese government can conduct will be able to sway the opinion of the American people. The US' own propaganda network is way stronger and will counter any Chinese propaganda with ease. I fully expect China to enact some kind of sanction in retaliation, but the idea that they could pull of a propaganda campaign that actually harms pelosi's standing is laughably unrealistic
Death to America