hhhmmm, I also just discovered that Firefox is a no go, when I started to test the application on https://meet.jit.si/. For me, Firefox is important, because our company does not allow any Google Chrome based Webbrowser, incl. Chrome based Microsoft Edge.
I had read an article on https://hacks.mozilla.org/2015/06/firefox-multistream-and-renegotiation-for-jitsi-videobridge/, which gave me the impression that jitsi would work on Firefox. The publication date is 2015, so it seems that this does not apply anymore to the current version Firefox v74.
I would be interested to know how high this issue is on the priority list of the developers team and to know what the planning is on the timeline to get jitsi compatible with the Firefox webbrowser.
May be Mr George Politis can shine his light on the time line and priority.
I look forward hearing from you. It really is a burning issue for my company.