In my opinion it does offer the best in class for anti-fingerprint features out of the box. Personally I don't use it because I need browser addons. Adding addons to mullvad kinda defeats the purpose, as they will make your browser extremely unique. Librewolf + addons is more fingerprintable, but still less so than Mullvad + addons imo. I feel like it is useful to have both; Librewolf + addons for your daily driver, and vanilla Mullvad for extra anonymous browsing, web searches, etc.
As a side note too, I have also heard that using Mullvad browser + Mullvad VPN is a bad idea, because it gives Mullvad as a company more information points that might potentially deanonymize you. Part of the reason why Mullvad is so great is that when an entity subpoenas your info, Mullvad can say "we don't know anything sorry." So the more information points you give, the more that defense weakens, even though Mullvad itself is trustworthy
I disagree; while Mullvad is very good with their no logs policies and collecting minimal info, it is generally good opsec not to centralize too many assets or data points into one company. Example: using android with chrome and google vpn, all your data is, from start to finish, in the hands of Google. Mullvad is miles better than Google of course, but I believe the same strategy applies