If your reported ROAS keeps drifting from what your bank account says, you're probably losing conversion signal in the browser. Ad blockers, ITP and consent gating drop a meaningful share of client-side pixel events before they ever reach Meta.
The fix is a two-part relay: a first-party pixel to capture the event on your own domain, and a server-side Conversions API call to send it — deduplicated by event ID — from your infrastructure, not the shopper's browser.
Done right, you recover the events the browser eats, keep attribution intact through consent changes, and give the ad platform cleaner signal to optimise on. The result is fewer phantom losses and campaigns that scale on real numbers.