Lars Brownworth wrote a significant post about the history of Jews in Byzantium:
“This kind of de jure restriction and de facto toleration didn’t inspire much loyalty from Byzantine Jews. In 556 there were riots in Caesarea serious enough to kill the governor, in 608 the Patriarch of Antioch was seized and dragged through the streets by the local Jewish population, and in 614 the Jews of Jerusalem sided with the invading Persians and participated in the wholesale slaughter of their Christian neighbors. When a Jewish leader was asked why he had participated he responded with the answer: ‘because these Christians are the enemies of my faith’.”
and
Further reading:“In fact, Jewish ancestry doesn’t seem to have been particularly troublesome for a man on the rise. One 9th century Byzantine Emperor (Michael II) had Jewish grandparents and grew up in a mixed household that retained many Jewish customs. Though called the “Amorian” (ie from the city of Amorium) he was the probable ancestor of the Leo the Wise and was therefore the true founder of the Macedonian Dynasty- the most brilliant family that the empire ever produced.”