Backing up Humbabella here; I’ve heard people apply the word “uppity” to their own race as well; in both the black and white communities. It feels like it is often applied when the speaker feels that the person in question is acting at a higher social rank than they feel that they should have achieved, regardless of the person’s actual social rank or if it is above or below the speaker’s social rank.
It intersects with racism and sexism in that the speaker often feels that all people of the races or gender identities that the speaker hates without reason should be of a lower social rank than they are.
While by all accounts her majesty the Duchess of Sussex is a charming, intelligent, successful person who had great success before her marriage; I can understand why sexist and racist half-wits would call her that since she has achieved perhaps the highest social rank in the world and her behavior is quite appropriate and gracious for that ranking.
