Firefox has introduced a new feature called Privacy-Preserving Attribution (PPA) that collects user data for advertisers by default, sparking controversy among users who feel that this move contradicts the browser's emphasis on data protection. The feature is enabled by default, and users must manually opt out. The data is anonymized and aggregated on a server, but critics argue that this still poses a risk to user privacy. Mozilla has faced criticism for not being transparent about the feature and for making it difficult for users to opt out.