Step-3: Graphql authentication issue

I tried generating multiple access tokens but still getting issues with authentication. The issues are as follows:

POST https://api.github.com/graphql 502 (Bad Gateway)

I tried the [ApolloStudio](https://studio.apollographql.com/org/bharathreddymaram1s-team/graphs/onboarding/cloud/endpoint-details), even there I got this message:
Your API responded with a 401 status code. You may need to specify auth headers to introspect your schema.Hide details
{ "message": "This endpoint requires you to be authenticated.", "documentation_url": "https://docs.github.com/graphql/guides/forming-calls-with-graphql#authenticating-with-graphql" }

Tried authentications: "Fine-grained personal access tokens" and "Personal access tokens (classic)".

Someone, please help