It seems like Google Chrome is not able to be pinned at taskbar on Kubuntu.
Does anyone know why this is the case?
I can pin/unpin Google Chrome without issues.
Pinning
Unpin option
It's possible something has gone wrong on your system.
Can you pin Google Chrome successfully if you set up a new user account?
To set up a new user account, open System Settings > Account Details > User Manager > New User.