Is the Metadata URI in one of these formats?
https://${yourOktaDomain}/oauth2/${auth_server_id}/.well-known/openid-configurationhttps://${yourOktaOrg}/.well-known/openid-configuration
https://developer.okta.com/docs/concepts/auth-servers/#org-authorization-server-discovery-endpoints
https://developer.okta.com/docs/concepts/auth-servers/#custom-authorization-server-discovery-endpoints