You did call userinfo as documented here Using OIDC to get OAuth Access Tokens | Twitch Developers ?
You didn’t get picture back either which suggest something is awry.
Here yoru claims lack " so this suggests your Claism are not JSON encoded correctly, and URI encoded
it should be more like
https://id.twitch.tv/oauth2/authorize?client_id=MYCLIENTID&redirect_uri=URIENCODEDREDIRECT&response_type=code&force_verify=true&scope=openid&state=cX98K%2FvC1yBBCnMZBh0Fag%3D%3D&claims=%7B%22userinfo%22:%7B%22email%22:null,%22email_verified%22:null,%22picture%22:null,%22preferred_username%22:null%7D%7D
Which’ll display something like (it might display like this even with invalid claims)
