There were reports that Jews helped the Persians capture certain cities and that the Jews tried to slaughter Christians in cities that the Persians had already conquered but were found and foiled from doing so. These reports are likely to be greatly exaggerated and the result of general hysteria.
Nehemiah ben Hushiel was described as a leader of the Jewish revolt against Heraclius. Nehemiah ben Hushiel appears in the 7th century Jewish book Sefer Zerubbabel where he represents the Messiah ben Joseph.
After the combined forces of Persia and the Jews captured Jerusalem in 614 CE without resistance, Nehemiah was then appointed the ruler of Jerusalem. He began the work of making arrangements for the building of the Third Temple, and sorting out genealogies to establish a new High Priesthood.
Jews did help liberate Jerusalem from Roman occupation. The son of the Babylonian Exilarch led a Jewish army to liberate Jerusalem. But they were an auxiliary force, not the ones who actually took the city. It was just easy to blame them exclusively, ignoring what the Persians did in other cities around the Eastern Roman Empire.