While criticism of Israeli policies and actions is part of that discourse, certain forms of anti-Israel rhetoric and activism delegitimize Israel and its existence, and are antisemitic when they vilify and negate Zionism – the movement for Jewish self-determination and statehood – or utilize anti-Jewish tropes or hold all Jews responsible for Israel’s actions.
They try to portray zionism this way in order to legitimize settler colonialism, and equate anti-zionism with antisemitism. Historically this chance was lost well over a century ago. See quote above from Jewish Voice for Peace and their site for details.