Fedora KDE spin has a package wl-clipboard and the wl-copy command in that package has a --clear option that the wl-copy man page says “clear the clipboard so nothing is copied”
But when I use the wl-copy --clear command and look in the KDE clipboard it is not empty. Why is that, is the wayland clipboard distinct from the KDE clipboard?
KDE’s clipboard applet remembers history of previous data that have been in the clipboard, and it’s separate from current clipboard value that Wayland knows about. I’m not aware of any command-line tool to clear clipboard history but it wouldn’t surprise me if there is one.
You can do it via D-Bus: gdbus call --session --dest org.kde.klipper --object-path /klipper --method org.kde.klipper.klipper.clearClipboardHistory