“If I encounter a word I do not know used by communists, it must be from 4chan because I am the most highly educated and professional person ever to walk the Earth.” — liberals

(I am Jewish and have been terminally online for years and have never heard that ‘slop’ is anti-semitic. Sounds like libs are just using anti-semitism as an empty accusation to silence communists to me, especially heinous when you consider who funded the Nazis in the first place and who rescued the Nazis after the Soviets destroyed them.)

It's their way of saying "low quality", usually thrown at things they deem forced by a marketing team. Always gave me some anti-semitic vibes when I used to see it used in context but I'm not sure why off the top of my head.