Mozilla's study of nearly 25 million Firefox users found that its fingerprinting protections cut the share of uniquely identifiable users from 75% to 46%. That figure is measured against simulated commercial fingerprinters. Mozilla says some protections are on by default only in Private Browsing, and Strict Enhanced Tracking Protection applies them to all windows.
Large-Scale Measurement and Real-World Mitigation of Web Browser Fingerprinting in the Wild
A large-scale study of browser fingerprinting based on telemetry from almost 25 million Firefox release users, and the mitigations it produced.
fingerprinting.study