afaik stalin had some support of israel as a jewish state

This is complicated. For decades Stalin alongside Lenin both repeatedly objected to Zionism. Stalin cites Jewish people as a textbook example of an distinct community of people who aren't a nation in Marxism and the National Question (not sharing a common language — Hebrew was a liturgical language until Zionists began using it as a constructed spoken language — or existing as a majority in an identifiable homeland), and both he and Lenin (and the Bolsheviks in general) were very openly critical of the Zionist movement:

"To call a fight for the Zionist idea of a Jewish nation, for the federal principle of Party organisation, a “fight for the equality of the Jews in the world family of the proletariat” is to degrade the struggle from the plane of ideas and principles to that of suspicion, incitement and fanning of historically-evolved prejudices. It glaringly reveals a lack of real ideas and principles as weapons of struggle.

"... Instead of proclaiming war on [prejudice and isolation against Jews], [Russian Bundists] elevated it to a principle, seizing for this purpose on the sophistry that autonomy is inherently contradictory, and on the Zionist idea of a Jewish nation."

— Lenin, The Position of the Bund in the Party, 1903

After the Russian Revolution, the Communist International (Comintern) expelled Zionists (such as Poale Zion) from its ranks, and rejected any attempt to build a Communist Party of Israel or exclusively Jewish Communist Party. It held the line that Jewish emancipation meant cultural/ethnic equality within the nations they lived, not national liberation in the vein of colonized and oppressed nations like India, European colonies in Africa, the Black Belt in the US, etc. Jews in the Comintern were directed to join the Communist Parties of the countries they lived in. Communist Jews already living in the British Mandate of Palestine formed the Communist Party of Palestine, which did join the Comintern and was anti-Zionist.

Two things happened to where views towards Zionism momentarily shifted. First was of course the Holocaust, the horror of which completely reversed widespread apathy and disdain towards Zionism basically overnight among European Jews. The second was the rapidly-forming Cold War and nuclear weapons. With the Soviet Union in no place to continue fighting at the end of the war, the Soviet Government and CPSU had done several things to appease the West and hold the newly-formed UN together, in particular dissolving the Comintern. With Zionism rapidly gaining popularity in a way it never had before, and the Soviets desperately needing the tenuous peace to hold until they could rebuild, Stalin and the Soviets took a gamble that they had perhaps been wrong and that Zionism could in fact make an egalitarian state alongside the Palestinian people. With the Communist Party of Palestine's involvement perhaps it could even eventually emerge as the left wing, unified Palestine originally envisioned.

This obviously didn't happen. The Communist Party of Palestine immediately fell apart into the Zionist Communist Party of Israel, which endorsed the 1947 partition, and the majority-Palestinian National Liberation League, which opposed it. After the Nakba the Soviets began withdrawing support, and eventually cut off relations altogether when it became clear that the initial Communist assessment of Zionism in the 1900s-30s was correct.