When a Jewish person expresses anti-Jewish ideas, is that antisemitism? It might sound odd, but yes. From the Middle Ages until the present day, there are plenty of examples of Jewish people perpetuating antisemitism, despite being Jews themselves. Sometimes it is what scholars call "internalized racism," which is something that many minorities, including Jews, have experienced. Other times, Jews attempt to separate themselves from other Jews as a defense mechanism. But whatever the reason behind it, antisemitism from Jewish people is no more acceptable than antisemitism from non-Jewish people.