Hi @zedeleyici
Thanks for contacting the Auth0 Community.
The id_token variable that you pasted is the JWT (json web token). If you paste this into https://jwt.io/ you’ll see the sub value which will be the user_id. Please review https://auth0.com/docs/secure/tokens/json-web-tokens/validate-json-web-tokens the recommended approach is to use verify() as opposed to decode(). You should be able to extract the sub value and use this in the endpoint that you mentioned.
Warm regards