On my machine, packagekitd never quits timely when zypper is manually invoked.
In fact, when KDE Discover is open then I've never ever seen it quit even after
minutes of waiting, and/or KDE Discover just keeps restarting it. Even without
any KDE Discover window open however, this usually never works for me in any
reasonable manner. Basically, the ask-to-quit mechanism might as well not
exist. It's possible I'm doing something wrong, but I haven't figured out yet
what it is.

This problem seems to be made worse by the fact that "systemctl disable
packagekit" doesn't seem to work. Neither does "killall packagekitd" due to
some apparent bug or config issue with killall on openSUSE, meaning I have to
type killall -9 /usr/libexec/packagekitd and repeat that in a fast manner a few
times until it finally stays terminated. I haven't found any other reliable way
of dealing with it. I'm even thinking about just downright deleting the
packagekitd binary, despite the caveat of that breaking KDE Discover.

I assuming users are probably not meant to desire to delete packagekitd, so
maybe this technical hiccup would be worth addressing if that's in some way
possible.

packagekitd version: 1.2.8

zypper version: 1.14.71