Lotta people died and much of GDR was essentially resettled by Nazis from West Germany. The east German children raised there in the years since did so in extreme poverty (for like first 10 or 20 years), all the while bombarded with anti-communist propaganda. Very much recommend checking out some of Ghodsee's work like Red Hangover.
I believe it was the Red Hangover episode where she goes into Germany. It was very fucked up. West Germany basically forced like a kind of reparations on the people of East Germany; stole their land, dismantled their public services and industries. She mentions a World Bank study where they measured the heights of East Germans that grew up during the years following reunification and found they were inches shorter than normal, exhibiting the type of pediatric malnutrition you would expect from someone in a famine or something.
Edit: Keep in mind she can be kind of lib and she's a huge fan of Alexandra Kollontai(who is cool), who was often at odds with Stalin. So she is very much not a fan of him.
One part of the answer would certainly be material conditions. It's easy to support socialism when it has given you a job and a place to live, but since "reunification", vast parts of the economy were dismantled and the free market was unleashed, leading to widespread poverty, brain drain, all the good stuff. And it seems to me that poverty leading people to support fascism always wins out over having received an anti-fascist education, unfortunately. Still, the Left is more popular in the East than the West, but who knows if it's due to the legacy of socialism or just because of regional differences within the party.