Some HP printers (driver: hplip) require a binary plugin: https://developers.hp.com/hp-linux-imaging-and-printing/binary_plugin.html This plugin is downloaded and installed when running the command "hp-setup" as intended by HP. If the printer gets configured automatically by KDE, this plugin is missing and the printer doesn't work. KDE should either detect that a plugin is required and run the command "hp-plugin" (part of hplip) or provide a starter button for "hp-setup" in the printer configuration dialog of systemsettings.
As the owner of one such printer, this would be very nice to have. :)
Is this still a thing that we want to add to the KCM? It's unclear if HP is supporting this on more modern printers as IPP Everywhere is an established thing, however, for some older printers this appears to be needed for advanced features.
Update: the printer was such a colossal pain in the butt that I replaced it with one that doesn't have this requirement. It was not expensive. I do still have the old one around and can use it for testing purposes, but IBH I don't see this as something with a high effort-to-reward ratio. These printers are like 10-15 years old and the proprietary plugin breaks constantly, needing manual re-installation. Better to junk the hardware IMO...
Then, yeah, let's close this