Followup: It does work for me after all, but the server was way too overloaded to serve it promptly.
Worked for me on Windows 11 Firefox 109.0 64-bit
ff 50, linux, works.
Firefox 50 was released like a week after Trump was elected. They do have an LTS version if you just want stability: https://www.mozilla.org/en-US/firefox/enterprise/ Or it was just a typo I don't know sorry