For example, the ability to disable global shortcuts on specific windows. So if I've got a remote desktop open to my work I can send Super-. (Win-.) and that'll open the Windows emoji picker in the remote desktop instead of the KDE one (locally). And it will remember this setting for that application!
I did not know this! I'll look into this and no longer will it piss me off when I tap Super in a VM to open the menu, and have to dismiss my local menu first.