Thank youI did some digging on this and also with help from @Immigration_guru what I understand is that, the background check is part of security.
Security check is done by Canadian intelligence and security agencies, with or without cooperation of proper authorities in countries you lived/stayed in, and it is done completely independently from IRCC - IRCC only gets result, which will be positive or negative, without any explanation (as it is classified). Basically, once IRCC gathers the results from all agencies they pass security within few days.
Wishing you a speedy PPR.