Subdomain Rerouting Separates Customer-Portal Data From Main-Site Data in CrUX

The Chrome User Experience Report (CrUX) system logs real-user performance data but aggregates it strictly by origin, not by domain portfolio.

Nicolas Hodin observes that authenticated customer portals on banking and insurance sites sit on a separate domain or subdomain, which makes them two different sites for CrUX.

Migrating the logged-in state to a dedicated origin (such as espaceclient.domain.com) physically severs the dataset.

As a result, the main site's field metrics in CrUX sometimes come out good, because the customer portal's data is not part of them.