Firefox loss in market share is more complicated. It's mostly due to growth in areas Firefox never had a foothold. Mainly the mobile browser and the Asian market (which mostly is mobile on top of it). On the desktop front in US and especially Europe the situation isn't nearly as dire as the global stats imply.

Firefox Android recently implemented extension support, so perhaps we will see some increased use there. But the majority of mobile users simply don't care and considering how interlocked Google and Android is, there is little hope for a third party browser gaining a foothold.

Brave had a lot of controversies and that's because their aggressive marketing strategy is so expensive. That's why they did shady stuff like hijacking links and insering their own affiliate codes. Something I don't want Mozilla doing with Firefox. Also Brave uses Chromium and the future of Chromium seems bleek. If it actually starts disabling support for adblock extensions then Brave has no future at all.