Some people use the prefix "zio", which was literally popularized by antisemitic white supremacists and fascists. I don't like that term for the reason that it originated from the far right.
Its ok to criticize Zionists. Zionism is itself the word Zionists use to describe their ideology, and it's ok to say things like "Zionists are wrong" or "Zionism is terrible" or even "the Zionists are promoting a modern form of fascism". There is a World Zionist Organization, and Zionism is the official ideology of the state of Israel.
It's not ok to adopt the vocabulary of David Duke, or antagonize Jewish leftists who point it out.