My grandmother grew up in Ukraine when it was pat of the USSR. She despises Ukrainians, claiming they were worse than the Nazis. When I ask her about Stalin, she says he was among the better leaders of the USSR, in terms of treatment toward the Jews. From my understanding however, Ukraine was devastated under Stalin's rule, whether it be pogroms against Jews or famines against Ukrainians in general. So, what was it really like for Jews under the Stalinist regime, pre WWII, during WWII, and after WWII?
In the memoir Babi Yar: A Document in the Form of a Novel, the author noted that there were many Ukrainian nationalists as well as those who are opposed to Stalin viewed the German invasion as an opportunity for independence, so it's a "my enemy's enemy" situation for them. They ranged from assisted the Nazis in rounding up the Jews to unwilling to help the Jews either due to leftover antisemitism or fear for their own lives. In one chapter the author wrote about a boy escaped into their backyard, his grandmother wanted to hide the boy, but their neighbor locked the boy up and gave him to the Nazis. I think this might be partly the reason why your grandmother feel this way about Stalin.