This is a standard feature of many browsers, including Safari.
E.g: On OSX you can download a .dmg file or .zip file, and when opening the OS will warn: "XYZ is an application downloaded from the internet. Are you sure you want to open it?". The information about the origin of the file comes from extended attributes.
E.g: On OSX you can download a .dmg file or .zip file, and when opening the OS will warn: "XYZ is an application downloaded from the internet. Are you sure you want to open it?". The information about the origin of the file comes from extended attributes.
See: https://www.idownloadblog.com/2017/04/20/fix-application-fro...