The login experience in firefox is really poor, it's possible that you'll need to manually disable the tracking protection because this app relies on cross-site cookies to make the authentication flow work.

The in app experience is also poor, most of the time you'll be redirected to the web app which is not a great UX compared to other products.

It also miss a lot of features like vault export, to do that you'll need the desktop app and once you get it apparently the extension can decide to log you out and force you to start over with the login process (that -again- implies you have to manually disable things).