It seems you don't have an OAuth2 authentication and instead support OpenID Connect, which is cool but there's no way to manually override the discovery info and just set the needed urls. Discord doesn't provide a discovery for OpenID Connect.
Fusion auth has an example of setting up Discord auth with OpenID Connect here: https://fusionauth.io/docs/v1/tech/identity-providers/openid-connect/discord
Notice that they can override the 3 endpoints.
