Discord doesn't let users use outdated versions while also updating too sporadically, which makes it terrible for packaging in distros. So these scripts provide a way to install it manually to /opt/Discord{,PTB,Canary} via the stable/ptb/canary scripts. Do note that you have to run them as sudo, verify what the scripts do before you run them.
Also change DATADIR and BINDIR variables before running to match your distros.
DATADIR="/usr/share"
BINDIR="/usr/bin"
By default, discord{,-ptb,-canary}.desktop is installed in /usr/share/applications/ and icons are installed to /usr/share/icons/.
There is also a FLAGS variable to automatically set some flags when launching with the .desktop file, by default --disable-smooth-scrolling --ozone-platform-hint=auto --enable-experimental-web-platform-features flags are set.