How to properly add a Requires for "I want a desktop" (or maybe "I want a KDE Plasma desktop")?

Hi all, I found tail-tray, a KDE Plasma tray application for tailscale. I have a first rough package (that I need to test), but was asking myself how to properly add a dependency on "a desktop environment. If I understood this properly, this tray app should be running fine on a KDE plasma desktop. Maybe also on other desktops, if everything follows the same "tray specification". No idea. But how to add that Requires? What should I depend on?

https://build.opensuse.org/package/show/home:ojkastl_buildservice:Branch_net...

Kind Regards Johannes