Full Answer

The change boils down to one thing: Google removed the quiet workaround that had been masking broken consent implementations for years. Before June 15, Google Signals acted as a secondary data path — if a site's Consent Management Platform failed to fire ad_storage correctly, Signals could still relay enough behavioural data for remarketing audiences and Smart Bidding to function. Store owners rarely noticed the gap because their campaigns kept optimising.

After the cutover, that path closed. ad_storage is now the single control point. A CMP that initialises too late, sends an incomplete signal, or defaults to denied without a proper prompt means Google Ads gets nothing for that session — no conversion, no audience signal, no bidding data. The practical impact hits WooCommerce stores hardest, because most rely on a consent plugin that was configured once and never re-tested (Data Transmission Control compounds the problem by adding a separate account-level toggle most store owners don't know exists).

The fix isn't complicated, but it is urgent. Audit your CMP's consent mode integration, confirm ad_storage fires on page load with the correct default state, and verify the signal reaches Google's tag before any conversion event fires. A Tag Assistant trace takes five minutes and shows exactly whether ad_storage is arriving or not.