Across the past year, a consistent pattern has emerged: marketing effectiveness is being eroded by a structural decline in signal quality across major advertising platforms. This shift is occurring independently of any finalised privacy legislation. It is operational, observable and already affecting performance.
Many CMOs are still waiting for Tranche 2 of the Privacy Act reforms before taking action. The belief is that the right time to modernise data foundations is once legal obligations become clearer. That assumption is flawed. The performance impact is happening before the regulatory impact.
What is changing today is not the legislation. It is the platforms.
In 2025, Google increased its reliance on modelled conversions due to tightening visibility at the browser level. Even though third-party cookies remain in Chrome, Google expanded aggregated and privacy-safe measurement across GA4, Chrome and Ads. Advertisers without strong first-party identifiers see:
These are observable outcomes across many accounts, not speculative risks.
Meta’s optimisation has become significantly more dependent on server-side signals as iOS restrictions and browser privacy controls reduce the reliability of pixel-only data. Advertisers with high-quality Conversions API implementations typically see:
Pixel-only accounts show more inconsistent optimisation in many environments.
Other channels have shifted similarly: