@Thespidersweb - if you mix with decent people, and are not Jewish yourself, or have close Jewish friends, then I quite understand that you might genuinely have never come across Antisemitism in RL.
But it does exist, and is far too prevalent. One example that brought it home to me. A good friend had cancer, she was being treated at the Homerton hospital in London. Because of chemo hair loss she was wearing a head covering, one of those stretchy but nice looking hat/scarf things. She'd treated herself to a few.
She was sitting in the garden courtyard area and a couple sitting near her started making the most awful antisemitic remarks, loudly and pointedly. She said she was shocked that anyone would do that in a public place where they would be overheard - until she suddenly realised that she was meant to overhear - that the remarks were aimed at her - they thought she was from the local orthodox Jewish community, because of the head covering. It shook her to the core and she felt guilty that she hadn't challenged them, but she was weak from chemo (which is why she was in there) and died a few months later.
She was not naive about prejudice and hate crimes, she had mixed-race children, but she had no direct experience of antisemitism until that point.
IMO Most women have experienced, and can spot, sexism and misogyny, most people of colour have experienced, and can spot, racism, most jews have experienced, and can spot, antisemitism.
sometimes it's overt and targeted, like the awful experience of @Dilbertian's DS, sometimes it's more "subtle" but it's all real and very toxic.