i guess this is where the differences in “common” knowledge comes in…
There are multiple countries where left wing politics is associated with anti semitism. It might seem weird but it’s true. Start with the UK - there is a Wikipedia page on it. I’m not going to share a heap of further context as I’d invite you to read and review yourself and come to your own conclusions, much as I have.
I would also encourage spending as much time reading accounts of world war I, and the conditions before and after the war, as you have on wwii. It helps to understand what left and right wing have meant over long periods of time, and the clumping / allegiances that comes with these alignments, which persist into the modern world without really being visible under the glossy label.