think quite a lot of what we see online from the political left is more anti religion than it is anti Jewish. People don't like religion, they don't really understand that Jews are a people as much as a faith, more so much of the time.
I think you're being much too generous, there TBH.
A lot of the Corbynites and similar had very clearly arrived at a very anti-Semitic position by the route of deciding that Muslims are the National and International underdogs, and then - well who knows exactly- but then it became quite an extreme position, but very obviously widely held. I still don't believe that Starmer has stamped it. It's more that he's smoothed it over. The JC front page before whichever election that was, was so, so powerful.
And yes OFC it's all about the numbers. About voting blocks as well as ideological support for the "underdog". I remember being told in an RE class (in north London) 30 years ago how big the British Jewish population was versus Muslim and how the Muslim population was expected to multiply through the 90s and 00s. I was really surprised at the time because I had a north London teenage perspective.
It really worries me now, because it's broken the surface and I don't see it going away, but I can also see that it's largely invisible to people with no experience of Judaism (secular or whatever), although I can't quite work out why it's invisible to them. Probably the thing of being so deeply embedded in the culture.