Is there any professor in a university in Germany or Austria who thinks that the nazis were lefties?

[Yeahsayyeah]

If you mean "history, political science or sociology professor", then probably not.

[Yeahsayyeah]

If you mean "history, political science or sociology professor", then probably not.

But do you have some cranks in the STEM fields or Law that do?

None, that I am aware of at the moment. But the question used "think", not "state" so, who knows. E. g, here are really some right wing law professors, where one could think a rationalisation à la "the Nazis were/are left-wing could come handy. And there could be experts in one field that hold crackpot views in another, but are usually not open about that (of course, covid-19 has changed the part about openness a bit).

[Yeahsayyeah]

Probably Hans-Hermann Hoppe. But like most terrible thinkers (Mises) he found himself in the dumpster of ideas - the American libertarian movement.

Oh, I totally forgot about this guy, but technically he is not a "professor in a university in Germany". On the other hand, his argument would probably more like..."democracy, communism, national socialism, social democracy and American liberalism are all just tools to expand state activity, centralize political power, spend money and diminish freedrom"

[Yeahsayyeah]

The German ambassador answered that he had never seen this debate in Germany.
I wanted to know if there could be some younger crank the ambassador didn't know yet.

There surely isn't an academic debate about that and I have never seen it outside the internet. Of course, we also have internet-libertarians and internet-conservatives who want to push this narrative. The first ones to declare "All statism is created equal" and the others to relieve and whitewash their own ideology.

But there are differnces. Some have heard of Georges Sorel as a source of Mussolini's thinking and so National Socialism as a variety of Fascism has to be left-wing. Others try to argue that Fascism is only an Italian movement and the Nazis are not fascists, but somehow socialist. And one crackpot came up with the idea that National Socialism was invented by the Czechs because...well, they had the Československá strana národně socialistická which name could be translated to "national-socialist".