Considering that traditionally the left-wing took its political thoughts from people like Marx and Trotsky and nowadays from Chomsky, I can't see how that is possible.
You really don't see how that's possible? Far left political thought (although I use the term "thought" very loosely) is totally entrenched in the 'oppressor-oppressed' narrative there is no room for nuance or flexibility. So for those - including intersectional feminists - who have jumped on the CRT bandwagon for instance, they see Israel and Jews as oppressors, so there is effectively no room to accommodate Jews in this rigid theory. Which is a shame because it would be a very useful framework for analysing antisemitism.
Marx - there is a MASSIVE scholarship on Marx' own antisemitism, prevalent in both his private and published writing. How could you not have known about this if you're quoting Marx as a driver of left wing political thought? Trotsky - if you want to find out how antisemitism has absolutely festered amongst contemporary Trotskyist groups I really urge you to read this. Because it will show you exactly how it "is possible". Please, please do read it.
https://fathomjournal.org/antisemitism-and-the-left-a-memoir/
And yes, I know Marx was Jewish. Jews can be antisemites too, although often it's hard to ascertain whether it's a genuine loathing of Jews/self hating or just part of their grift. So the less I say about Chomsky the better - suffice to say I'm fed up of non-Jews throwing Chomsky (and Pappé and Mate) in our direction as if we've never heard of them before, and often the said poster only found out about them five minutes ago. Mainstream - including left wing - Jews have serious issues with their work and there's a reason they get ridiculed as cranks.
Fortunately there are many, many Jews around the world protesting against the treatment of Palestinians
Yes, I'm appalled at what's happening in Gaza. However I also count myself as a Zionist so I find this statement utterly fucking offensive:
However Zionists love to make out that you have to prove that you don't hate Jews by embracing the genocide of Palestinians.