New notarization requirements from macOS 10.14.5 onward

We’re working with developers to create a safer Mac user experience through a process where all software, whether distributed on the App Store or outside of it, is signed or notarized by Apple. This will help give users more confidence that the software they download and run, no matter where they get it from, is not malware by showing a more streamlined Gatekeeper interface. Learn how to get your software notarized

Source: developer.apple.com