It’s kind of one of those old-timey ones. I think I’d hear old farts saying that one was I was real little and my parents just told me it was thought of as antisemitic at that time (this was the 1970s). I remember a teacher explaining the same thing in sixth grade, IIRC. The old farts I’d hear saying that one, would be the same types that would not think twice about saying how someone “jewed them down” on a price negotiation. It’s one thing not to know the Shylock connection, but using Jew as a verb is quite another. They’d also say things like someone “gypped” them, but that one stuck around for a lot longer in mixed company, JFC. I think part of the reason is that there are very few Gypsies in the USA and a lot of people honestly didn’t really make the connection between that term and the people.