Idk, its never stopped working for me for the past 10+ years. And Firefox has additionally always supported ctrl-n and ctrl-p working in the address bar for suggestions while Chrome has never supported this
Bit late to reply, but seems ^A and ^E (jumping line begin and end) at least do work in Firefox.
But for example ^T (letter transpose) do not work on macOS Firefox, which I'm quite accustomed to use also. But ^T works fine same macOS Safari and Chromium.
Firefox apparently has its own input method which do not implement all what macOS supports.
