If it bothers you that the meanings of words change, you'll be getting more upset every year.

"Identitarianism" has been traced to Adorno, who used it differently than later right and leftwingers used it. English. It just won't stay in one place.

The Oxford English Dictionary traces the word to 1943 and offers this definition, which is consistent with the way leftists use it today: "An ideology or political agenda which seeks to defend or promote the interests of a particular social, racial, or religious group, nationality, etc. Hence: advocacy of an ideology or a political agenda specific to one's particular religion, race, nationality, etc."