Hello,
I am not aware of any Discord application list as we have for Facebook for example. I just checked this and could not find one either.
Means, you need to find a manual way based on URL host or destination IP property. Do you know if Discord Chat has a specific URL like https://www.discordapp.com/chat? Because then you could create a rule like:
URL.Host equals "www.discordapp.com" AND
URL.Path equals "/chat" AND
Authentication.Username is in list <Discord chat allowed users>,
Action: Stop Rule Set
Some websites share a list of their services + URL hosts + IP addresses and ports online (e.g. Microsoft) which can then be used for proxy bypasses.
Regards,
Marcel Kutrieba
Technical Support Engineer