https://blog.mozilla.org/en/firefox/fingerprinting-protections/
In a major privacy upgrade, Mozilla has introduced new anti-fingerprinting measures in the latest version of its Firefox web browser, Firefox 145. These enhanced protections aim to significantly reduce the number of users vulnerable to digital fingerprinting, a tracking technique that can identify individuals across websites and browsing sessions.
The new defences, initially available only in Private Browsing Mode and Enhanced Tracking Protection (ETP) Strict mode, add randomised noise to background images, restrict the usage of local fonts, report a limited number of processor cores, and more. As a result of these measures, the percentage of users who can be uniquely fingerprinted and persistently tracked has been reduced from 65% to just 20%.
Mozilla explains that this phased approach to enhancing Firefox’s anti-fingerprinting capabilities is necessary to maintain a balance between privacy and usability. While aggressive blocking can reduce trackability further, it may also impair the functionality of legitimate websites and tools that rely on real-time data. The browser now provides users with the option to selectively disable the new protections on specific sites if they encounter any usability issues.