I assigned a KDE action to caps-lock key (so that cap-lock is a hotkey for that) hoping it will be disabled (a trick working for other keys). But it was not.
Why this happens and how to find a better way to disable caplock (something more acceptable than this)?
So to System Settings, then click on "Input Devices" under "Hardware", then click "Keyboard", "Advanced".
Make sure that "Configure keyboard options" is selected. Then select Caps Lock key behavior > Caps Lock is disabled