For me that didn't work. The red badge on System Preferences disappeared, but it came back the next day. Doing a `defaults delete com.apple.preferences.softwareupdate LatestMajorOSSeenByUserBundleIdentifier` got rid of it permanently.

Sorry I missed the second half, I fixed my comment:

> sudo softwareupdate --ignore "macOS Catalina"

It uses the label in the software update catalog to filter out specific updates.

You can get rid of it with:

> sudo softwareupdate --reset-ignored

I'm not sure why people seem to think this is related to Catalina. This popup has appeared nearly every day for years. I'm pretty sure it shows up for any minor system updates, not just major version upgrades.

I want to be notified of new security updates that need to be installed. The problem is that it's now appearing every day even if there aren't any.

I thought that was a joke for some reason!