I was wrong about Stalin, he was anti-semitic even at the time of the Molotov-Ribbentrop Pact. I have just looked it up.
'During his meeting with Ribbentrop, Stalin promised him to get rid of the "Jewish domination", especially among intellectuals.[18] After dismissing Maxim Litvinov as Foreign Minister in 1939,[19] Stalin immediately directed incoming Foreign Minister Vyacheslav Molotov to "purge the ministry of Jews", to appease Hitler and to signal Nazi Germany that the USSR was ready for non-aggression talks.'
In 1931, Stalin had said,
Stalin's 1931 condemnation of antisemitism[edit]
"On January 12, 1931, Stalin gave the following answer to an inquiry on the subject of the Soviet attitude toward antisemitism from the Jewish News Agency in the United States:
“
National and racial chauvinism is a vestige of the misanthropic customs characteristic of the period of cannibalism. Anti-semitism, as an extreme form of racial chauvinism, is the most dangerous vestige of cannibalism.
Anti-semitism is of advantage to the exploiters as a lightning conductor that deflects the blows aimed by the working people at capitalism. Anti-semitism is dangerous for the working people as being a false path that leads them off the right road and lands them in the jungle. Hence Communists, as consistent internationalists, cannot but be irreconcilable, sworn enemies of anti-semitism.
In the U.S.S.R. anti-semitism is punishable with the utmost severity of the law as a phenomenon deeply hostile to the Soviet system. Under U.S.S.R. law active anti-semites are liable to the death penalty.[10]"
en.wikipedia.org/wiki/Stalin_and_antisemitism
So, Stalin was anti-semitic and other Russian communists were too