Checks for the presence of the 'Referrer-Policy' header, which protects data from being leaked to insecure origins.
The Referrer-Policy header determines how much information is put into the "Referer" request header when making additional requests on the page. This should be used to limit the amount of information shared with insecure or 3rd party origins.
This test will look for the presence of this header and check to make sure it isn't using an unsafe or invalid value. For a list of all possible values for this header, please read our documentation on the Referrer-Policy Header.