WI the Third Reich formally declared that "Jews are not human beings, and they shall not be considered persons for any legal or moral purpose?"
I would guess the POD might be early in the Reich, when the pretense of "legality" still existed in the government, maybe as an adjunct to the infamous Nuremberg Laws.
One can argue this was already de facto the case, but making it de jure greatly introduces the possibility of greater extremes, such as:
1) Passports are not issued to non-human creatures, preventing the escape of many Jews before 1939.
2) Eating Jews is no longer considered cannibalism. Rounding up Jews for slaughter for Aryan dinner tables becomes a real possibility. (Though I would guess another killing mechanism than cyanide would have to be used. Would cyanide affect the meat?)
3) Would the international community accept the German position that "Jews are not people" as a valid exercise of national sovereignty? Perhaps this keeps outside groups from trying to help the Jews in any way, such as taking in those who manage to escape.