Full Answer

iOS 14.5 ATT was the single biggest event — it cut Facebook's visible conversion data by up to 38.41% as iOS users opted out of tracking. But sudden drops often signal something changed on your end: a plugin update broke your pixel, an audience exhausted, or a creative ran out of steam. The critical distinction is attribution drops vs actual performance drops. If your WooCommerce orders stayed flat while ROAS cratered, Facebook simply stopped seeing conversions — not because fewer sales happened, but because ad blockers and iOS restrictions hid them from the pixel. Server-side tracking via Facebook CAPI recovers these lost conversion signals by sending purchase events from your server, regardless of what the browser blocks.