Mozilla faces complaint over Firefox's hidden "privacy preserving" feature

European privacy group noyb filed a formal complaint against Mozilla for quietly enabling a feature in its Firefox browser that tracks user behavior without consent.

The feature, called "Privacy Preserving Attribution" (PPA), allows Firefox to store ad interaction data directly rather than relying on individual websites.

The move has drawn comparisons to Google's controversial "Privacy Sandbox."

While Mozilla claims that PPA is a less invasive alternative to traditional cookie tracking, noyb argues that it still violates user rights under the European Union’s General Data Protection Regulation (GDPR).

According to noyb, Mozilla enabled PPA by default in a recent update without notifying users or asking for consent, contradicting its reputation as a privacy-friendly browser.

Felix Mikolasch, a lawyer at noyb, criticized Mozilla for adopting what he sees as an industry-driven narrative that legitimizes tracking, arguing that PPA adds to, rather than replaces, existing tracking methods.

The complaint requests the Austrian Data Protection Authority to investigate Mozilla’s practices and calls for the deletion of unlawfully processed data.

Millions of European users may be affected by this change, raising concerns about how Mozilla balances privacy and ad measurement.