Discord is imported from Arch, and it is out of date there too. If you want to have quick updates to Discord, best bet is to use the AUR version of Discord so when there is an update you can update it through Pamac or any other AUR helper immediately (because community update the AUR PKGBUILD rapidly and no need to go through the distribution update normal process, but I see it is also out of date on the AUR right now). So other best bet is to install Discord locally so you can manually update it yourself.
//EDIT: to install locally, download the compressed archive on their website, extract the Discord folder somewhere in your home, and you can start Discord executable directly, or you can also modifiy the Discord.desktop file to change the line Exec= to point to where you extracted it (you can also modify the Icon= line to point to Discord icon in the local installation folder), and move the Discord.dektop file to ~/.local/share/applications/ so it is available in your Application launcher (in theory). Then you could manually extract new update when needed over this local installation. At this point if it works you can also uninstall Discord from the package manager (or keep it and use it, and only use the local installation as a fallback when it doesn’t update quick enough on the distribution package).