Rakuten is an affiliate marketing leader and is among the first ones who started to support server-to-server tracking. When using a custom domain, s2s tagging relies on first-party cookies, which live longer than third-party cookies. Increasing cookie lifetime considerably affects affiliate marketing results and affiliate commission.
When a customer clicks on an affiliate link, their click is tracked and stored as a first-party cookie in the user’s browser. When the customer completes a purchase, the order information is passed back to the Rakuten server, with the click ID from cookies and order parameters configured in sGTM.
So if you're looking for a more accurate and reliable way to track your sales, you should consider using Rakuten's server-to-server tracking.
1. Rakuten server-to-server tracking
2. How to set up server-side affiliate tracking using server Google Tag Manager