I think most countries that support Ukrainian have already said as much. China and Russia will vote down anything in the UN as two permanent members of the security council.

Because after surviving the Holocaust the state of Israel was formed by expulsion of natives, colonialism, war and, possibly, genocide.

https://en.wikipedia.org/wiki/Israeli_war_crimes https://en.wikipedia.org/wiki/Causes_of_the_1948_Palestinian_expulsion_and_flight

I would recommend starting with the history of Israel from the First World War and going chronologically. It is a messy conflict with stupid numbers of massacres and atrocities by the PLO, Israeli government and both of their predecessors.

Long story short though. Israel and the PLO have, with certainty, committed various “war crimes” in the past. As Israel won the war(s) the loser of those wars can very easily claim Genocide. If it was the other way around with the PLO winning the wars then we would see the reverse right now.

Accusing someone/a country of a crime does not mean they did it. Being a victim in the past (Holocaust) does not mean that they are immune to criticism/criminal proceeding for future actions.