In a future version of macOS, notarization will be required by default

For example, if a Print Dialog Extension (PDE) that provides fax services wants to access a user’s contact list, the host executable must declare the and include the purpose string in its Information Property List for the plug-in to operate. For more information about how to use the Xcode UI to upload your software, see Upload a macOS app to be notarized. Upload your software to the Apple notary service, as described in Upload Your App to the Notarization Service.

Source: developer.apple.com