Ksnapshot was for KDE 4 (no longer maintained), Spectacle is now the app KDE/Plasma developes for screenshot, installed by default in KaOS, and also by default accessible with the Print Screen key.
To use search in Octopi, there also is the option under Search to use
By Description, that option would have shown you Spectacle when searching with
screenshot. (or use pacman directly
pacman -Ss screenshot)