The International Holocaust Remembrance Alliance (IHRA) has created a definition of antisemitism that includes the question of when does criticism of Israel morph into Jew hate. This definition has been adopted by many nations, is used by the US State Dept and over 35 US States. It is very reasonable and fair, which i why it is so widely acknowledged and used:

Accusing the Jews as a people, or Israel as a state, of inventing or exaggerating the Holocaust.

Accusing Jewish citizens of being more loyal to Israel, or to the alleged priorities of Jews worldwide, than to the interests of their own nations.

Denying the Jewish people their right to self-determination, e.g., by claiming that the existence of a State of Israel is a racist endeavor.

Applying double standards by requiring of it a behavior not expected or demanded of any other democratic nation.

Using the symbols and images associated with classic antisemitism (e.g., claims of Jews killing Jesus or blood libel) to characterize Israel or Israelis.

Drawing comparisons of contemporary Israeli policy to that of the Nazis.

Holding Jews collectively responsible for actions of the state of Israel.