According to: https://auth0.com/docs/api/authentication#get-token-info the /tokeninfo should be deprecated instead of /userinfo, which you say in your code that should not be used.
This endpoint is part of the legacy authentication pipeline and will be disabled for those who use our latest, OIDC conformant, pipeline. We encourage using the /userinfo endpoint instead. For more information on the latest authentication pipeline refer to Introducing OIDC Conformant Authentication.
According to: https://auth0.com/docs/api/authentication#get-token-info the /tokeninfo should be deprecated instead of /userinfo, which you say in your code that should not be used.