if for some inscrutable reason you decide to use a new name for the same product, at least update the default shortcuts KDE comes with. i had to update on each and every computer the shortcut for the Prnt key, just because for no sensible reason the binary's name changed from the rather self-explanatory "ksnapshot" to the completely unrelated "spectacle" Reproducible: Always
I remember having this issue when upgrading Plasma on Arch, but it was a matter of changing the settings. It probably should have happened automatically. Some other comments on this matter: https://www.reddit.com/r/kde/comments/3yrv1e/plasma_55_default_printscreen_shortcut_with/