They claim a 'cloud provider' they use went down and that's what caused all of this. The real question is why is there an always-on cloud connection in Firefox and why is it so important that the browser stops working if that server can't be reached. Super fishy....
https://twitter.com/firefox/status/1481657624651313
Edit: originally linked tweet was deleted https://twitter.com/firefox/status/1481657624651313155