Unemployment changes

We had filed with the full unemployment and it was accepted right before the new tax law went into effect.  We were told to do nothing, but I did do an amended return just in case, but didn't file.  The IRS sent us the regular refund and just got the remainder from the exclusion of the unemployment.  My amended return shows a difference of $6,800 and the IRS only sent us $3,400.  Any clue?