The badge notification is because it wants me to upgrade to Catalina. I never want to upgrade to Catalina because my hardware is too old to be run under any newer version of MacOS than I already have.
How can I dismiss this particular notification or otherwise make the notification badge go away?
I tried System Preferences --> Notifications, to see if I could disable all badge notifications from the System Preferences app, but that doesn't appear to be an option. And really, I don't want to disable all notifications from System Preferences, I just want to tell it to to stop nagging me about the Catalina upgrade.