GraphQL Tracing is a feature that, when enabled, provides detailed timing information about the execution of a GraphQL query. While useful for debugging and performance optimization, it can potentially leak sensitive information about the server's internal workings when left enabled in a production environment.

When tracing is enabled, the GraphQL server includes an `extensions` field in the response, containing a `tracing` object. This object includes detailed information about the execution of each resolver in the query, including start times, end times, and durations.

Example of a response with tracing enabled:

```json
{
  "data": {
    "field1": "value1",
    "field2": "value2"
  },
  "extensions": {
    "tracing": {
      "version": 1,
      "startTime": "2023-09-17T10:00:00.000Z",
      "endTime": "2023-09-17T10:00:00.050Z",
      "duration": 50000000,
      "execution": {
        "resolvers": [
          {
            "path": ["field1"],
            "parentType": "Query",
            "fieldName": "field1",
            "returnType": "String",
            "startOffset": 1000000,
            "duration": 2000000
          },
          {
            "path": ["field2"],
            "parentType": "Query",
            "fieldName": "field2",
            "returnType": "String",
            "startOffset": 3000000,
            "duration": 1000000
          }
        ]
      }
    }
  }
}
```

Security Impact of GraphQL Tracing:
- **Information Disclosure**: Tracing data can reveal internal details about the GraphQL server's structure and performance, which could be leveraged by attackers to plan more targeted attacks.
- **Performance Overhead**: Enabling tracing in production can introduce unnecessary performance overhead, potentially impacting the server's ability to handle high loads.
- **Data Privacy Concerns**: In some cases, tracing data might include sensitive information that shouldn't be exposed to clients.