Even Vivaldi has started saying certain plugins may not work in the future because they don't abide by Google's best practices.
My biggest problem with Firefox is Google meet does not work well with it in Linux. It can take me over a minute to coax the video to work and some builds the audio just never works. A lot of other stuff I use works slow or just poorly in Firefox. I need OWA and PWA's to work, keeping all of my work things together is just a really big hassle.
I primary Librerwolf, and slip over to Vivaldi or Brave when I have to have something that's google-ish. Each of the three are loaded down with the plugins that I use regularly and bookmarks are kept synced.