Fans quickly pointed out that she looks… well, black.
(Blackface has an ugly history in the United States, dating back to "minstrel shows" in the pre-Civil War era. Non-white people would paint their faces black and draw exaggerated lips and other features to make themselves look like hideous stereotypes of black people. The practice has persisted in pop culture, reappearing frequently at racist frat parties and sometimes on celebrities.)
Jenner deleted the photo, but one person caught a screenshot: