In level flight induced drag is not proportional to lift, or
it would be constant as lift is. Induced drag is proportional to CL squared -
alpha squared.
At the stall CL begins to fall, but it is still high. Alpha is still high and
therefore induced drag is still high. Profile drag is rising as the airflow
separates and breaks down. Overall there is a small drop in CL and a continuing
rapid rise in CD