You have it backwards. Antifa ( Antifaschistische Aktion) was the paramilitary arm of the German Communist Party in the early 1930's. They pre-date the Nazis coming to power.
Above, the 1932 Antifa conference, from The Lost History of Antifa
The current antifas are not the same. They only appropriated the German communist labels of the 30s, but their real lingusitic origin is that of methods the Soviets used in prison camps to experiment how fascists could be turned into Stalin’s favorite soldiers. These Germans were called antifas.
The same experimental results are applied to today’s KKK democrats who have “repented” to stalnism after social pressures and constraints, massaged into it