In Pew’s recent polling, 27% of Jews identified as “Jews not by religion” — marking “no religious affiliation” or “other,” then indicating Jewishness in a follow-up.
The percent of Jews that voted Mamdani is likely closer to 40%.
Exit polls indicate Mamdani won nearly 1/3 of the Jewish vote. He probably won a majority of Jews under 30.
The self-appointed leaders of the Jewish community don't speak for vast - vast - numbers of Jewish Americans.