Hi! I'm using Arch (fresh install about 3 days ago) with Xorg, using PulseAudio (on PipeWire 1.2.7), Discord stable 348981 (ff756ae) Host 0.0.76 x64 version, with 6.12.1-zen1-1-zen kernel.
When I install discord, I notice that Discord now supports and provides "Also share audio system" feature. So i try it immedietly. At first, it doesn't work, Idk why, but I assume this is because only missing some packages/configurations on my fresh installed Arch. Simply, I install the VLC media player (sudo pacman -S vlc) then reboot the system, and then the features for sharing the audio system works well.