Just a note here, the socialists in Germany were also opposed to the Nazis. Yeah I know, many right wingers can not understand how that was possible. But Hitler knew how to ignore labels, he sent both socialists and communists to concentration camps too.
The thing you call “communism” was really just a form of autocracy that is functionally indistinguishable from the plutocratic regime that lies at the endpoint of Republican plans and policies. In new-speak, it is packaged as “freedom”.
The thing I call communism is the thing Lenin, Mao, and Stalin were part of.
Lenin and Stalin being noted German communists, Mao being Austrian doesn’t make the list of noted German communists.