I don't understand why whatever team that works on Firefox removed keybind settings from Firefox, based on what I have read trying to find a method, keybind settings used to be a thing and then just got removed. Now I'm sure you have heard everything about this, but have you considered that on your march to the most secure and safe browser, that adding settings for keybinds might be better than having the users crawl the internet for whatever app, shady or not, they can get their hands on to fix it for them. Possibly breaching their safety in the process over a simple setting. Personally all I want is to disable the keybind for muting tabs, as its the same keybind I use to mute on many other programs, and as such is quite annoying. (Now if I am somehow wrong and there are keybind settings hidden away, accessible to me without breaching my safety, I welcome you to share.)