Adam Clarke on 2 Chronicles 36:22

Now in the first year of Cyrus - This and the following verse are supposed to have been written by mistake from the book of Ezra, which begins in the same way. The book of the Chronicles, properly speaking, does close with the twenty-first verse, as then the Babylonish captivity commences, and these two verses speak of the transactions of a period seventy years after. This was in the first year of the reign of Cyrus over the empire of the East which is reckoned to be A.M. 3468. But he was king of Persia from the year 3444 or 3445. See Calmet and Usher.