It doesn't seem to have occurred to anyone on the left that the only culture that is upset by "cultural appropriation" is the culture of the Gramscian-Marcusian left (which arose in Europe, Gramsci and Marcuse like their intellectual forebearer Marx, being white males).
Actual Mexicans who are living in Mexican rather than Gramscian-Marcusian culture think Cinco de Mayo is silly, but aren't particularly offended, just as people who are actually living in Chinese culture think a white American woman wearing a qipao is a compliment to their culture, not something to get angry about. Very traditional Native Americans tend to understand American Indian mascots as a tribute to the martial virtue of their forebearers (generally human sports mascots that aren't a peculiar tie-in to local history are tributes to martial virtue, my absolute favorite being the Yeshiva University Maccabees), while Native Americans and white "liberals" who are part of Gramscian-Marcusian culture are (or pretend to be) horribly offended.