There are ethical concerns, half the Mozilla board resigned over Brendan Eich's appointment as CEO of Mozilla, and Brave is his new venture after essentially being ejected from Mozilla: https://en.wikipedia.org/wiki/Brendan_Eich#Mozilla
I want nothing to do with such a divisive character like Brendan, thus I'll steer clear of Brave.
Mozilla itself says, and I say, that "half the board" did not resign over me. See https://blog.mozilla.org/blog/2014/04/05/faq-on-ceo-resignat..., and also https://news.ycombinator.com/item?id=10654651 for a detailed breakdown from me based on what I can say that others involved also said. Mozilla (same FAQ link) testifies that I was not "ejected" and was welcome to stay at an unspecified C-level executive position. If you don't believe them, I can't help you.
On "divisive", beware false division and fake cover stories or excuses. https://news.ycombinator.com/item?id=13429898
Neither is great though.
>There is probably no corporation that has fooled its userbase more and for longer than Mozilla. Pretending to be your friend, it has for years ruined the customizability, privacy, and usability of its browser. The marketing team was, and still is, in full swing trying to spin every one of its shitty decisions positively. [...] The amount of spyware in both these browsers is massive - FF has the most, but it can all be disabled through an user.js script
There's no denying that there have been some fuck ups in Mozilla in the past but it seems to me like the author has an axe to grind here. If they don't then they should at least reference their claims.
I mean they call IE, Chrome and Opera "Botnet web browsers". I suppose they're referencing the 4chan meme and not actually saying that these browsers contain botnet code but I'm not sure if that makes it better.
As the website says your best options are GNU IceCat or Ungoogled Chromium with uMatrix and HTTPS Everywhere.
If the author listed more precisely their problems (like you just did for instance) then the reader could make an informed choice. Saying "Chrome is a botnet and Firefox is filled with spyware" is hogwash and disqualifies this page completely IMO.
People will not start suddenly compile their own browser or dig github for browser they never heard of.
They use Google and Gmail. Firefox surely knows that 70% of people will be pissed right there if google is not default browser so they atleast get money from google for it. It's compromise.
They need money to compete with mainstream browsers and they have to make smart decisions about which compromise to make.
Signal is getting similar shit for using google services for messaging. But it makes e2e encryption mainstream.