Antisemitism can be defined arbitrarily by Zionists. Criticizing Zionism is often labeled as antisemitic. You cannot win by playing this game.
The easiest is to ignore this label and look at the facts. If I am an antisemite for not wanting psychopaths to kill Palestinian children, and want said psychopaths to be justly charged for their crimes, then so be it, I am an antisemite. I don’t care.
We generally overrate labels. Labels can always change their meaning depending on who you ask, and this meaning is manipulated to gain political points.
Majority of people here do not oppose Jews based on nationality and only stand against Israeli army and government committing war crimes and inflicting massacre on Palestinian civilians. Good luck twisting that.
I think it crosses into antisemitism when any/all Jewish people are targeted. Like the people shouting “death to all Jews” have certainly crossed that line.