I have been trying to change KWin's global shortcuts, e.g. for switching virtual desktops or the 'present windows' effect.

I'm not sure if my memory plays a trick on me, but I believe there used to be a separate component "KWin" in the sidebar. Since at least 5.13.0 KWin's shortcuts can now be found in the "System Settings" component.

I'm not sure if that's a bug or intended, but fwiw I didn't expect KWin's shortcuts in this group... I rather expected it to only contain shortcuts for, well, the app called "System Settings" (the very app I'm using to change these settings).

Since this component only contains a tree of settings for window management functions (which again is also called "System Settings" - a bit redundant maybe?), maybe it should be renamed? I understand that "KWin" might have been not ideal either, since it might not mean much to the average user, how about renaming it to "Window Management" (a term used throughout the settings experience)?