I Built a Pre-Block Pixel Interceptor to Fix Our 38% Meta Signal Loss. Here's the Code.

We were losing 38% of our purchase signals to Meta. Not misattributing them — losing them entirely. Meta's pixel never saw them. Neither did our ad algorithms. We were optimizing Advantage+ campaigns against 62% of our actual customers. This is how we fixed it without paying $150/mo for Google Cloud sGTM. Why Pixels Die Before They Reach Meta Standard ad pixels fire an outbound HTTP request from the visitor's browser: user converts → fbq('track', 'Purchase') → https://connect.facebook.net/... Ad blockers intercept that request at the network level. uBlock Origin, Brave, Firefox Enhanced Tracking Protection — all block connect.facebook.net by default. iOS Safari adds another layer: ITP (Intelligent Tracking Prevention) nukes client-side cookies after 7 days, breaking the identity chain entirely. The result: any user who bought 8 days after their first ad click is invisible to your pixel, even if they convert. We measured this against our Shopify ground truth and found: GA4 : 16% signal