This is interesting. I gave up on FF years ago due to poor performance. I find Opera to be a nice reliable browser also, but haven't dug into the security aspects of it.
At this point, there are really only three browsers. Chrome & Chromium based browsers; Firefox; Safari.
Opera, Brave, Microsoft Edge, etc. are all Chromium, which is the core browser functionality from Chrome itself. None of these are truly private and won't really secure your PII. Brave claims to be, but the problem is, its still Chrome in the end, and Google, well, they ARE the one who wants all your personal information. So, its just not private, and it never will be. Google has gone out of their way to find ways to track you and everything you do online with their browser tech.
FireFox was a dog, but with the release from this summer, they made TREMENDOUS strides and their browser is now competitive. It is also highly secure, very private, and actively tries to hamper tracking by web sites, web trackers, data brokers, etc.
Safari is...still a dog. It lags quite far behind in terms of modern web standards support. Apple seems to loath the web, because it threatens their app store revenues, so I don't expect much improvement here. It should be more secure and private than Chrome/Chromium, though.
On phones, there is also the "DuckDuckGo" browser option, which is also a more private browser. Similarly, the DuckDuckGo search engine minimizes what tracking it does...just enough to make search work.