Full Answer

Platform data misalignment has two causes: input differences and model differences. Input differences arise when platforms receive different data — one fires from client-side JavaScript and loses events to ad blockers, another receives a complete server-side feed, and a third misses transactions because the confirmation page loaded before the tag fired. Model differences arise because Facebook uses multi-touch attribution with view-through credit while GA4 uses last-click within a session.

Server-side tracking fixes the first cause entirely. By capturing purchase events from the WooCommerce order hook and distributing them to GA4, Meta CAPI, Google Ads Enhanced Conversions, and BigQuery through a single server-side pipeline, every platform receives the same events with the same transaction IDs and order values. The data enters each platform's attribution engine identically. No events are lost to ad blockers. No events are delayed by consent banners. No events are duplicated by page reloads.

The second cause — model differences — remains, and it should. Facebook's view-through attribution genuinely measures something different from GA4's last-click model. Both are useful perspectives. The problem is not that models disagree; the problem is that without clean input data, you cannot tell whether a discrepancy reflects a model difference or a data gap.

With server-side alignment, the remaining variance between platforms becomes interpretable. A 15% gap between Facebook and GA4 conversion counts can be confidently attributed to view-through credit rather than to lost events. That interpretability is what makes cross-channel budget decisions possible.