<p>Despite extensive corporate social responsibility (CSR) research, previous studies have insufficiently examined how consumers evaluate LGBTQ+-related CSR under rising concerns about authenticity and rainbow-washing. To address this gap, this study explicitly distinguished between perceived proactive (value-driven) and perceived reactive (pressure-driven) LGBTQ+-related CSR and tests how they shape brand attitude and four dimensions of online brand advocacy (OBA). Using survey data from 385 Gen Z consumers in Vietnam, we find that perceived companies proactive LGBTQ+-related CSR strengthens brand attitude, whereas perceived reactive LGBTQ+-related CSR does not significantly reduce brand attitude. Brand attitudes, in turn, predicts all four OBA dimensions. Importantly, persuasion knowledge weakens the effect of brand attitude on OBA behaviors for higher-effort behaviors (brand defense, information sharing, and brand positivity) but not for the low-effort virtual expressions, suggesting that symbolic online support can persist even when consumers are more skeptical about persuasive intent. Theoretically, this study extends attribution and social identity perspectives by revealing how authenticity judgments translate into differentiated advocacy behaviors. Practically, it provides guidance for managers on designing credible LGBTQ+-related CSR strategies in emerging markets. This study is among the first to differentiate proactive versus reactive LGBTQ+-related CSR and to examine their distinct downstream behavioral consequences.</p>