JAC officials have not made a statement or retracted the cutoff list so I don't  think it is a mistake. I have check the official cut off list for IGDTUW CSE. And your category is OBC category.  There might be a number of reason it might be decreasing instead of increasing . One of them being that there might be a lot of applicant trying to get IGDTUW through OBC quota and thus they might had to decrease the cutoff. For further queries you should contact the JAC examination cell.