I have given up on installing .deb packages, except in the rare case of it being my only option. If you can't install Discord or other apps from the main repositories, I would consider using snaps and flatpaks. I installed Discord easily through flatpak and it works just fine. Try this:
sudo apt install flatpak or
sudo apt install snapd
flatpak install discord
snap install discord
It should install discord and it will run like any other app.
Time is precious. Waste it wisely.
Just because something is illegal, doesn't make it wrong. Just because something is legal, doesn't make it right.