Problems with Firefox 85.0.2 on Windows 10 Pro

I’m exploring switching from LP to BitWarden.

First step was to create a new BW account. In Firefox, I submitted the create account form, and a message slid in in the upper right, roughly, “An error has occurred”. Tried again, same thing, reloaded the page, same.

I successfully created a new account in Chrome, and sent myself a verification email. Since I already had email open in Firefox, I clicked the verification button in the email, and got the same error. I copied the verification URL into Chrome and it worked.

Tried to log in to the site in Firefox, same error.

So I have a new BW account, but I’m concerned that it’s not super stable, and Firefox is so mainstream, it’s worrisome. (I’m a web developer, so I use Firefox and Chrome regularly, other browsers less but some.)

Has anyone run into this?
Over time, has BitWarden been stable in people’s experience?
Other thoughts?

Don’t know how I missed this before, but the Firefox dev console shows that the response to my login attempts is 415 Unsupported Media Type.

I’ve disabled all extensions, still not working.

This actually works for most people?