Here "You will" refers to the people of Jerusalem. But, "you fled" refers to their ancestors since this describes an event that happened many years earlier. Alternate translation: "You will flee just as your ancestors fled" (See: [[rc://en/ta/man/translate/figs-explicit]])
Here "in the days" is an idiom that refers to the time when Uzziah was king. Alternate translation: "when Uzziah was king of Judah" (See: [[rc://en/ta/man/translate/figs-idiom]])