https://www.404media.co/google-microsoft-meta-all-tracking-you-even-when-you-opt-out-according-to-an-independent-audit/

An independent webXray audit of more than 7,000 California websites found that Google, Meta, and Microsoft often continued tracking users even after opt-out signals were sent. The report says 55% of sites still set ad cookies after opt-out, with reported failure rates of 87% for Google, 69% for Meta, and 50% for Microsoft.