Notice how one of the underlying messages of the cartoon is that it’s Zionist Karen that is the real antisemite: by deeming that those demonstrating against the killing of children are antisemite (literally: against Jews), she is implying that killing children is a Jewish thing to do.
This is very much the kind of racism displayed by those who equate anti-Israel with antisemitic: they’re implying that Israel and its actions are all core Jewsih chracteristics, de facto slandering all Jews including those who disagree with Israel and/or its actio s, so they’re the ones who by definition are antisemite.