You seem to be talking about the Dyke March in either Chicago (2017) or DC (2019). In both cases, it was only flags with a central Star of David that were banned, and solely because of their similarity to the Israeli flag. So you seem to be misrepresenting the facts a bit.
I don't necessarily agree with their choice on that, but in the 2019 march at least, they were allowing any Star of David pride flags where the symbol wasn't central; they were suggesting it be in a corner. It wasn't about "Jewish symbols", it was about nationalist symbols. Explicitly.
And sure, while some antisemites use antizionism to hide their views, some antisemites use zionism to hide their views. A lot, actually. Christian Zionism isn't exactly a secret movement.
Conflating Israeli symbols with Jewishness is precisely the problem. You need to be able to separate the two issues, the same way that attacking China for its abuses of the Uighur peoples (among other things) isn't an argument that Chinese culture or traditions or Chinese people in general are "bad", it's entirely about the political structure.