YaST, zypper and packagekit

I know how to use YaST and zypper to manage my software packages, but the other day I discovered that something called packagekit was also active on my system. (I have disabled it.) How does packagekit relate to YaST and zypper? Are they aware of each other? Does packagekit have access to my repository list, and does it update things in the background without my knowledge? I wonder, because my desktop has been behaving strangely, and a new release of it has been published, to which I have not yet explicitly upgraded. Leslie -- Distribution: openSUSE Leap 15.3 x86_64