The last chapter of Jeremiah first recounts the fall of Jerusalem (1-11), the destruction of the temple (12-23), and the death and deportation of the people (24-30). Why? It’s one last confirmation that God did everythingHe said he would do through Jeremiah. Every one of Jeremiah’s prophecies - every last one - came true, because God is true. Always.
As we have noted in previous entries, Jeremiah’s prophecies did not have their intended effect, at least from Jeremiah’s perspective. The more Jeremiah preached and prophesied, the more the people became more and more intransigent in their rebellion. It is likely they did exactly what Peter would later say not to do, in 2 Peter 3:8-9 - do not think that just because God is not presently judging your sin that He will not in the future.
He is not slow. But He is merciful - He does not wish that anyone would perish, but in order to not perish, we must repent. Paul makes the same point in Romans 2:4 - that God’s mercy - the restraining of His hand of judgment - is not an end in itself. It has a purpose - to create within us gratitude for His mercy, and in that gratitude, that we would repent. God does not demand perfection, but He does require from us a turning from our sins, to Him.
That mercy rings in the final verses of Jeremiah (31-34). King Jehoiachin would never see Israel again. But he lives - the offspring of David, through whom God would keep His promise to David, and in time raise up a Greater David, to save us from our sins.