You cannot anonymize data and we've known this since the Netflix data was famously deanonymized. "Anonymized data" is what people call it when they're lying or

You cannot anonymize data and we've known this since the Netflix data was famously deanonymized. "Anonymized data" is what people call it when they're lying or don't know enough to be trusted with privacy. The primary issue is that data that seems harmless in isolation can be powerful in aggregate, that any data unique enough to be informative to a third party can be used to triangulate an individual's identity, and that data which cannot be matched up with a user today might be in the future when more information is available or statistical tools are improved. If Firefox actually does say they "anonymize" your data, that's a pretty damning indictment on their lack of trustworthiness and diligence.