The Referrer-Policy HTTP header governs which referrer information, sent in the Referer header, should be included with requests made.
Options:

• no-referrer - The Referer header will be omitted entirely. No referrer information is sent along with requests.
• no-referrer-when-downgrade (default) - This is the user agent's default behavior if no policy is specified. The URL is sent as a referrer when the protocol security level stays the same (HTTP→HTTP, HTTPS→HTTPS), but isn't sent to a less secure destination (HTTPS→HTTP).
• origin - Only send the origin of the document as the referrer in all cases. The document https://example.com/page.html will send the referrer https://example.com/.
• origin-when-cross-origin - Send a full URL when performing a same-origin request, but only send the origin of the document for other cases.
• same-origin - A referrer will be sent for same-site origins, but cross-origin requests will contain no referrer information.
• strict-origin - Only send the origin of the document as the referrer when the protocol security level stays the same (HTTPS→HTTPS), but don't send it to a less secure destination (HTTPS→HTTP).
• strict-origin-when-cross-origin - Send a full URL when performing a same-origin request, only send the origin when the protocol security level stays the same (HTTPS→HTTPS), and send no header to a less secure destination (HTTPS→HTTP).
• unsafe-url - Send a full URL when performing a same-origin or cross-origin request.

Specification https://w3c.github.io/webappsec-referrer-policy/#referrer-policy-header