Regarding notice under section

Respected Sir,at the time, when the CBIC has been waive off the penalty to filing the GST return w.e.f. July 2017 to April 2020 without any penalty or late fee.Sir at the time the has been filled his all' the GST returns and claimed the ITC paid on purchases.But now the department has been issued the notice to dealer disallow the ITC for the year 2018-19 by mentioning that the dealer was not claimed the ITC.Sir my query is that the. department has right to disallow the ITC whereas the dealer has been filled his returns at the time when the CBIC has waive off the penalty and the dealer has been claimed the ITC on his original and true purchases.Sir I also want to know that the dealer the ITC disallow by the department can be adjusted with the ITC in the hand of the dealer at present.Thanks