(The post says there are two comments but I can only see the usual one from the auto mod so I hope I am not repeating anything).

This is a great question because the myth was perpetuated in later years by the fact it wasn't properly addressed or talked about. For context, with the defeat of Nazi Germany, the newly established DDR created the narrative that with the help of the Red Army innocent workers and peasants were liberated from the oppression of Nazism and ready to rebuild (Aufbau) a better Germany. In this narrative, fascism had been utterly destroyed, removed, and annihilated from the newly formed nation. Saying that the working class of East Germany were innocent during the period of The Third Reich while in reality millions of Germans actively or passively supported Nazi rule created a conundrum that was purposely not addressed.

As you can imagine simply stating this as fact without confronting some incredibly difficult and pertinent issues created an undercurrent of problems.

With this state sponsored doctrine in tow, the DDR effectively exonerated its citizens from past wrongdoings and insisted anti-semitism or post-war fascism were problems for capitalist countries. A survey conducted in the 1960s concluded over half the population of the DDR believed they had been anti-fascists during the Nazi period. Education naturally forms the outlook of many people and looking into what they were taught gives an idea of what myths can and cannot perpetuate. On one hand, there were no efforts to give any credit to the Wehrmacht or the "ordinary soldier" which contributes to the myth as a whole. The history curriculum paid little credence to the Western Allies and almost entirely focussed on the Red Army and their sacrifice. The result was the resounding defeat of fascism with no quarter for feeling sympathy towards German soldiers who survived.

However, on the other hand, very little attention was paid to the plight of the Jews and other racial groups subject to genocide. Memorialisation entirely focuses on Russians, other Slavic groups, or the "martyrdom" of key Communist figures like Ernst Thalmann. It isn't until 1984 that references to six million murdered Jews were included in textbooks. Even more worrying is that textbooks actually portrayed Kristallnacht as an obvious result of capitalism and drops part of the blame at the door of German Jews. Overall there is an overarching attempt to highlight how capitalism was a constant contributing factor throughout the war such as the "IG Farben Cartel" which apparently organised the murder of camp inmates and insisted on experimentation. The reason this is relevant is down to the DDR's poor attempt at confronting the Holocaust and the anti-semitism that compounded it.

Surveys done on the eve of unification in 1990 specifically looked at xenophobia and anti-Semitism in East German society and demonstrated worryingly high levels of intolerance. In particular, young adults and teenagers were most susceptible to this (E.g. 25% of students at high school agreeing with the phrase "The Jews Are Germany's Misfortune"), all who had gone through the East German education system.

Ultimately the ways in which the DDR confronted a deep wound in society conflicted with the foundation stone of their political set up and Marxist-Leninist doctrines. With the latter triumphing over a societal need to reflect, accept, and repent, a particular form of ideology injected through a state-controlled curriculum was in charge. Although by no means did schools encourage aspects of the Wehrmacht myth themselves, they did leave issues regarding Germany's past horrors and complicity in the Holocaust in the dark resulting in vulnerable young minds more open to extremist views.

N.B: If you want more of a breakdown by category regarding the DDR history curriculum I am happy to send the article listed at the bottom.

References:

Fulbrook, M, The People’s State (New York 2005).

Fox, T, Stated Memory: East Germany and the Holocaust (New York 1999).

Kurthen, H, Bergmann, W and Erb, R (eds.), Anti-Semitism and Xenophobia in Germany After Unification (New York 1997).

Weger, G, 'The Legacy of Nazism and the History Curriculum in the East German Secondary
Schools', The History Teacher 25.5 (1994).