When I try to share one of my monitor's via WebRTC (e.g. https://www.webrtc-experiment.com/Pluginfree-Screen-Sharing) the options are the open windows and "share full screen", which is a combination of both my monitors. (1280x1024 and 1920x1080) I tested this with firefox 86.0 and firefox-nightly 88.0a1.20210301. To ensure it aren't addon's or a weird setting that I made that stop the screen sharing I used the command "firefox-nightly --profile /tmp/firefox-test" I use Arch-Linux with i3 as window manager with the X11 Server. I would except to be able to select the individual monitor's instead of the combination of all.