A lot of American leftists are so obsessed to American imperialism that they consider anyone/anything that opposes the US to be “the good guys” and any criticism of the good guys must only be because we bought into western propaganda. This sadly makes it pretty much impossible to really engage in any sort of meaningful discussions around criticism of China, because no matter what you say, you’ll either be assumed to be acting in bad faith, or you’re a useful idiot for some western government.
With all of that said, it doesn’t really have anything to do with Israel or anti-semitism, really, does it? Pretty much every leftist is justifiably critical of Israel, but also strongly opposes anti-semitism. People can be wrong about some things, but right about others.