When a user clicks a link or fetches a resource, the browser includes an optional Referer HTTP header. This header specifies the exact web page URL the request originated from.
Because query parameters and subfolder paths are stripped during cross-site transitions, marketing teams using tools like Google Analytics 4 (GA4) will notice a reduction in granular referral path details. While traffic is still correctly categorized as a "referral" from the root domain, the specific backend article or link that generated the click is hidden unless UTM campaign parameters are explicitly appended to the target URL. 🔒 Mitigating CORS Pitfalls strict-origin-when-cross-origin chrome