Monthly ITC Mismatched and GST Issued Show Cause Notice

Came to know that if there is No ITC Mismatched Found in yearly return (GSTR-9)

then it is not Punishable for ITC Mismatched in any month of said financial year

But GST Department Issued Show Cause Notice and Demand for ITC Mismatched 

for the month of Dec '20 and Jan'21

Question : Financial year 2020 - 2021 is running -- So Why GST Department Issued Show Cause

Notice and Demand GST for DEC and Jan 21 ???

Please reply ... thanks