Thanks for your answer. Do you work for Twitch? If yes, then please update the documentation, which is very misleading especially https://dev.twitch.tv/docs/authentication/getting-tokens-oidc/#oidc-authorization-code-flow where it links to the scopes available – and doesn’t mention at all that all these scopes are not honored.
Furthermore you can resolve the scope=<space-separated list of scopes> part with scope=openid since any other scope isn’t supported