I want to be clear that it matters whether you were actually talking about the Holocaust. If you were using this as an analogy, about anything less traumatic than the actual Holocaust under Nazi Germany, then I would argue that it is anti-semitic, because it belittles the degree of horror that occurred. Don’t compare other things to the Holocaust, that’s shitty.
The following assumes you were actually talking about the Holocaust (EDIT: or something equally bad):
Does it erase Jewish culture, history, or trauma? No, it’s clearly doing the opposite of that: affirming the trauma.
Does it dehumanize Jews? No. It’s neutral to the humanity of Jews, except insofar as it’s clearly meant to affirm the horrors of the Holocaust, which dehumanized and destroyed Jews and Jewish culture.
Does it perpetuate a harmful stereotype? Nope! It might be considered a stereotype that Jews know Hebrew, but it’s not a harmful one, and it doesn’t make the claim that all Jews know Hebrew in any case. In fact, it strikes back at the idea that specific facts about Jews are even relevant to the conversation about the Holocaust.
Most likely–if you were in fact actually talking about the Holocaust–the person you were arguing with just wanted you to go away, and gave you a bad faith rebuttal.
Edit to add: OP added context, and this conversation was about the Uyghur genocide. Clearly, the intention here was not to belittle the horrors of genocide, since it’s actually a conversation about genocide. Not anti-semitic.