Social media now exerts potent informal accountability pressures within China's corporate governance ecosystem. Analyzing 498 Weibo "Hot Search" ESG incidents (2017–2022) involving firms listed in mainland China, Hong Kong, and the U.S., we reveal a counterintuitive pattern: rather than catalyzing improvement, reputational shocks frequently trigger corporate retreat, especially on governance metrics. Domestic firms drive this effect, while overseas-listed counterparts demonstrate stronger ESG resilience, underscoring institutional quality's moderating role. Our findings contest three prevailing views: first, stakeholder pressure does not uniformly enhance ESG performance; second, governance dimensions prove uniquely vulnerable to reputational risks compared to environmental or social concerns; third, disclosure regimes alone cannot explain responsiveness differentials. Crucially, governance scandals precipitate avoidance strategies instead of reform, social accountability suffers from fragmented public engagement, and institutionalized norms—transcending disclosure rules—arm overseas firms against reputational storms. These insights equip regulators, corporations, and investors to navigate ESG accountability in algorithm-driven environments.