A bug is classified as something behaving without the intent it was created with, or is malfunctioning. This is not a bug. The Social Media Links tab has no observable bugs. This is an issue related to text filtering which needs to be specified in Chat/Text Review Requests. An alternative appropriate method would be a feature request or review request to unblock Discord from the social media tab, which encompasses all cases of this occurrence rather than a singular one - such has already been done.
The filter is very intentional. It may be an oversight on Roblox’s behalf to not apply the same filter to group social media links as game social media links, but the word Discord is not allowed on the site anywhere except where explicitly indicated that it is fine.
This doesn’t prevent you from linking your Discord either. Just call it something different for now.
Please use categories appropriately.