Just upgraded my MacBook Pro to macOS 10.15.4 (Catalina) from macOS 10.14.6. Everything went well AFAICT, except a badge remains on the System Preferences Dock icon. I go into the Software Update preference pane and it says everything is up to date. I tried
defaults write com.apple.systempreferences AttentionPrefBundleIDs 0; killall Dock
but the badge returns if I click on the Software Update pane. How do I get rid of this, now that everything is updated? (Or is everything not really updated?)