The "Marx hated Jews" thing comes from the fact that he wrote an essay titled "On The Jewish Question."
That phrasing raises alarm bells because we associate the term "The Jewish Question" with Nazis, but it was just the way issues like this were phrased within these philosophical circles. And honestly even beyond that it's more of a translation convention than anything else. You could just as easily have translated that title as "Regarding the Matter of Jews."
The essay is actually a response to another philosopher named Bauer, who claimed that Jews would only be liberated if they stopped being Jewish, because true emancipation requires secularism. The essays Marx is responding to are blatantly antisemitic, even by late-19th century standards. Bauer was arguing that Jews who wanted liberation from oppression were basically asking for "special privileges," (in an argument that bears some similarity to modern concepts of "reverse racism") and implying that Jews aren't even oppressed because they control the economy.
Marx's "On The Jewish Question" is basically him saying Bauer is dumb and wrong and antisemitic, and he's being deeply sarcastic for most of the essay.
He does so by throwing Bauer's antisemitism back in his face, by using a series of antisemitic arguments about how the real religion of the Jew is money and huckstering, and so if you want to abolish Judaism, you'd have to abolish economic exploitation. He's responding directly to Bauer's use of antisemitic tropes about how Jews control the economy. He's using Bauer's own antisemitic framework to prove Bauer wrong.
This also goes back to the conflict between Marx and the rest of the Young Hegelians (which Bauer was). He was constantly criticizing them for being too idealistic and abstract, rather than focusing on material realities. His argument here was "You're framing 'the Jewish Question' as if it's a theological problem, but it's not. It's a political and economic one." Because he was Karl Marx and that was his whole thing.
I really don't understand how anyone reads this essay as anything but sarcasm. I get that some of it is probably lost in translation, but the context makes it really clear that Marx is making fun of Bauer. The idea of Jews giving up their religion would have been deeply personal to Marx. He would have understood exactly what it meant for Jews to give up their religion, and how that was an act of oppression rather than liberation from it. Also, Marx and Bauer had already split by the time this essay was written, and they kind of hated each other. Marx wrote a lot of responses to/criticisms of Bauer, and he called Bauer a "right wing fanatic" multiple times.
Like, what's actually more likely here?
Option 1: Karl Marx, a Jewish man, wrote one essay that is totally at odds with all his other analysis on the nature of oppression to be rabidly antisemitic and then basically never discussed the subject again?
Option 2: Karl Marx, a Jewish man and a well-known lover of pettiness and drama, wrote an incredibly sarcastic essay making fun of a raging antisemite that he already he didn't like?
