I asked ChatGPT is similar question earlier this week. This was the answer.
While Mozilla has not been found to sell user tracking data in the conventional sense, the introduction of features like PPA (Privacy-Preserving Attribution) and changes in privacy policy language have understandably caused concern among users. These developments suggest a shift towards balancing user privacy with the need to support advertising models. Users prioritizing privacy should stay informed about these changes and adjust their browser settings accordingly.
I did a little checking and it all agrees with the reporting.