1) Use of German WWII equipment- the show uses mostly WWII era tanks (also including some pre-war and a handful of post-war tanks as well) from a variety of different countries. This means that it uses military equipment from Nazi Germany (with Nazi imagery stripped away though), including Tigers, Panthers, Panzer IVs, Panzer IIIs, Stug IIIs, Hetzers, Jagdpanthers, Jagdtigers, Elefants, Tiger (P), Tiger II, etc. Now there are a lot of different tanks from other countries as well mostly corresponding to what "nationality" each school reflects, and the protagonist school has a cosmopolitan assortment. I don't really think this is a problem.
2)Uniforms- The different schools have uniforms which are inspired by the various countries they are from. Some of the uniforms approach the uniforms worn by tankers or other groups from their countries. See below.
3)National stereotypes- (using analogues for simplicity's sake, all of the schools have their own names) The Italian school is filled with passionate girls who love food, the Finns steal equipment from other schools, the Germans are ordered and hierarchical, the Americans have the big money and carefree attitude, the British wants to be elegant, the Russians talk about "sending people to Siberia" and "general winter", the Japanese are bound by the tradition to charge into everything recklessly. Nothing really problematic IMO, it's all lighthearted and none is too scathing.
4)Name drops- Guderian, Rommel, Carius and Whittmann are all mentioned during the course of the show, but only in a purely military capacity. Granted, there is one girl in the Oarai history club that takes the name "Erwin" in honor of Erwin Rommel, but that's due to her passion for military history (her best friends in the history club also take historical names, I don't think one taking "Caesar" is a political statement. Also, the British ones are literally all named after various kinds of tea- "Darjeeling", "Rosehip", "Orange Pekoe".
5)Fanserivce and fanart- a handful of scenes from the show are fanservice-y, which is my least favorite part about the show. I won't be touching that, nor the problematic fanart. But problematic fanart exists for everything.
6)Iron Cross- the German school uses the Iron Cross as part of its logo. I don't think that's problematic- maybe I'm wrong.
