Since the the last big update in november this command now returns
warning: output HDMI-0 not found; ignoring
and it seems xrandr can no longer detect my second monitor. My second monitor is an lg tv connected via hdmi while my main monitor is connected via display port.
The second monitor that xrandr does not detect is LG Electronics LG TV. It works on windows. And the second monitor also does not work on gnome or on xfce where it used to work automatically without me having to use the xrandr command.
Possible that the new nvidia driver has a problem. Try to switch to an older driver. 470xx should be still available. It might be also a good suggestion to stick with a LTS Kernel (5.4 or 5.10) with a nvidia driver.
I would not say that xrandr has a problem here. It just do what it gets.