The intersection of (whether real or perceived) Jewishness and having ideas Hitlerists considered dangerous is the common denominator for most authors in the book burning. Not all, Hemmingway was already mentioned, and there were Jewish authors whose works were forbidden, but not publically burned under great fanfare. But the overwhelming majority of the burnings targeted those the nazis found particularly triggering, and that's usually Jew + something else that sets them off.

Magnus Hirschfeld was smeared as "Germany's most dangerous Jew" in the nazi propaganda outlets for his gender research and advocacy for legalizing gay sex, Einsteins and Freuds ideas were demonized by the nazis because they both ran counter to the fascist ideology and because they were Jews, Marx or Trotzki served as examples of "Judeo-Bolshevism", Heinrich Heine was a socialist and personal friend of Marx and Engels, anti-nationalist and of Jewish descend, gentile anti-war writers like Remarque were simply claimed to have been Jews, all because antisemitism was the connective tissue that held fascism together.

In the end, fascism is just an endless, utterly incoherent list of bigottries and grievances, and when you want to connect all of these bigottries and grievances in a way that manages to tiptoe around the actual connection, stabilizing capitalism in crisis by instrumentalizing all insecurities and hatreds of the common chud to forge the most brutal oppressive force possible and crush all dissent, you have to make up a conspiratorial "master bogeyman" who orchestrates all the people that nazis hate.

Historically, this was the Jew. Today, it still is, they just dogwhistle around it. But in the end, whenever they talk about "Globalists" or "gender ideology" or "postmodern neo-marxists", of "coastal elites" or "BLM-CRT-Antifa" what they are actually saying is "the Learned Elders of Zion."