The situation is actually worse than it looks.

This error exists because Apple has effectively made app notarization mandatory, otherwise, users see this warning. In theory, notarization is straightforward: upload your DMG via their API, and within minutes you get a notarized/stamped app back.

…until you hit the infamous "Team is not yet configured for notarization" error.

Once that happens, you can be completely blocked from notarizing your app for months. Apple has confirmed via email that this is a bug on their end. It affects many developers, has been known for years, and Apple still hasn't fixed it. It completely elimiates any chances of you being able to notarize your app, thus, getting rid of this error/warning.

Have a loot at how many people are suffering from this for years with no resolution yet: https://developer.apple.com/forums/thread/118465