This plugin keeps track of the referrer per WooCommerce order.
The Referrer-Policy HTTP header controls how much referrer information (sent with the Referer header) should be included with requests. Aside from the HTTP header, you can set this policy in HTML.
Many web browsers use the strict-origin-when-cross-origin
Referrer-Policy
HTTP header by default:
Send the origin, path, and querystring when performing a same-origin request. For cross-origin requests send the origin (only) when the protocol security level stays same (HTTPS→HTTPS). Don't send the Referer header to less secure destinations (HTTPS→HTTP).
In WooCommerce version 8.5.0
launched on January 8, 2024, the similar 'order attribution tracking' functionality has been launched:
https://woo.com/document/order-attribution-tracking/