Inspite of Josiah's religious reforms, God still punished Judah because

According to the biblical account in 2 Kings 23, God still punished Judah despite Josiah's religious reforms because Judah had committed many sins, including idolatry, shedding innocent blood, and practicing witchcraft. Although Josiah had overturned the religious policies of his father Manasseh and made efforts to eradicate idolatry and restore the worship of the true God, the people of Judah had already gone too far in their disobedience, and their faithlessness had become unpardonable in God's eyes. Additionally, Judah had also sold herself to foreign powers and continued to participate in sinful practices despite Josiah's efforts, leading to God's judgment upon the nation.