I recently decided to switch to the Brave browser, but have run into a rather significant problem. I actually love this browser far more than Firefox, but I can’t seem to log in to my Fastmail email account! I can see that this was a topic that was raised on December 16, but the suggested fix (disabling the shield) did not work.
Backup your data, download and install the latest Brave-Browser from here - https://brave.com.
Users should have migrated to the latest one by now but team seem to be stuck polishing the transition for the seamless update from the now deprecated Brave-Muon to the new Brave-Core (0.56.15).
Reply back if you still have issues in the latest version and be sure to input the About Brave info, OS, and change above title tags to the new version.