PeacefulPete has the right idea, the real 70 year curse was on Babylon . Most likely it was written about and these writings were later changed to make it as though it was about the desolation by Babylon of the areas around the levant then later changed again to make look as though it was talking only about the Jews.
This is not the only text found in the Bible that was stolen from another source then edited. Noah’s flood , Sampson and the writings of Anumope are just a few examples.