Girls und Panzer is Entartete Kunst - Degenerate art
and here why
1.The graphical part
Japanese animation and this anime are generally contrary to "National Socialist Realism"(Nazi Realism)
The combination of colors is not natural and is unusual for "normal viewer eyes". Not natural big eyes, not natural physiognomy. So, for example, modernism was banned, especially expressionism, and it appeared in the Weimar Republic, moreover, this is a phenomenon of freedom and fascist ideologies do not like it
2.Propaganda and ideology
Girls und Panzer is moe shit, that counter to Nazi ideology about representation of women as "Kinder, Küche, Kirche", and superiority of Germany over the global Jewish Anglo-Saxon world, commies,
And In this case, this anime literally is Kulturbolschewismus, or cultural marxism in english,