Jeremiah 40:13 – 41:15 elaborates more on the flight to Egypt. This flight was, as we read there, against the will of the Lord. The consequences thereof can be read in Jeremiah 44:1–30. In 2 Kings 25:26 it is only one announcement which confirms what it says in 2 Kings 25:21: the reign of Judah is over.
For the following part (2 Kings 25:27–30) see also the exegesis of 2 Kings 24:8–17. The mercy that the king of Babel extends to Jehoiachin can also be found in Jeremiah 52:31–34. Note that in 2 Kings as well as in Jeremiah, this is the conclusion of the Bible book. But 2 Chronicles does not mention this. The reason can be that Chronicles is written later and with a specific intent (namely, to urgently call the people to remain true to the service of the Lord, as it shapes up in the temple in Jerusalem). This being considered, it is not illogical that 2 Chronicles closes with the proclamation from King Cyrus to rebuild the temple in Jerusalem.
26 Then all the people, both small and great, and the captains of the forces arose and went to Egypt, for they were afraid of the Chaldeans.