Full Answer

The damage isn't random — it's structurally biased. Ad blockers disproportionately strip conversions from privacy-conscious, technically sophisticated users who also tend to be higher-value buyers. When Smart Bidding never sees those conversions, it learns to target the remaining pool: users on unblocked browsers with default settings. The algorithm isn't broken — it's doing exactly what it was trained to do, just trained on the wrong data.

Accounts with full-fidelity signal — Enhanced Conversions, server-side tagging, and Consent Mode v2 — hit their target CPA or ROAS 58% of the time, compared to 31% for default tracking setups (Visionary Marketing, 2026). That's nearly double the hit rate, and the mechanism is straightforward: better inputs produce better outputs. Server-side tracking tools like Transmute Engine route WooCommerce conversion events through a first-party endpoint that ad blockers can't intercept, restoring the missing signal to the bidding algorithm.

The practical test is simple: compare your Google Ads reported conversions against your WooCommerce order count for the same period. If Ads reports significantly fewer, your Smart Bidding is training on a biased sample — and every optimisation decision it makes compounds that bias. Stores that closed the gap by moving to server-side tracking typically saw Smart Bidding performance improve within two to four weeks as the algorithm retrained on cleaner, more complete conversion data (Google Ads Help, 2026). The longer the gap persists, the deeper the bias embeds itself into your bidding model.