There are better browsers than Firefox if you care about privacy. Both Brave and Tor have better results in this comparison that was shared here recently: https://privacytests.org/, same with this tool from the EFF https://coveryourtracks.eff.org/ it gives better results for Brave than Firefox (even with blockers installed on my Firefox). Mozilla themselves give the same score in their very limited comparsion: https://www.mozilla.org/en-US/firefox/browsers/compare/

Multi-account containers are really the only killer feature in Firefox for me, they're super convenient for my work, but that's about the only thing it has left going for it.