Having your browser lie about every detail is anonymous, but not k-anonymous. i.e. Nobody will know who you are, but your browser fingerprint is unique and so you will not blend in with everyone else. The Tor Browser and Mullvad Browser try to be k-anonymous, so everyone looks the same. Brave Browser is an interesting case where all fingerprint data is randomized, so you are not by definition k-anonymous, but you do blend in with all other Brave users in that it is all randomized in the same way for everyone.
In summary:
- Having your browser lie in a unique way is bad
- Having your browser lie in the same way as everyone else is good
- Having your browser lie in a random way like everyone else is still good