People tend to speak about hardened Firefox as a separate entity because, unlike some other browsers that come with default privacy out of the box, Firefox requires you to change some settings beforehand. However it's worth noting that a lot of this stuff is extremely quick and easy to do and you don't have to make the advanced changes if they are too confusing. You don't have to use a fork of Firefox either; the default browser is a very good option if you take 5 minutes to set it up and retains QoL features like sync that some forks remove.