FastAPI service in Snowflake Container Services returns Snowflake UI HTML instead of API response

I have deployed a FastAPI application in Snowflake Snowpark Container Services (SPSC), and while the service appears to be running successfully, when I hit my API endpoints, I'm getting Snowflake's default UI HTML response instead of my FastAPI JSON responses. Environment

Platform: Snowflake Snowpark Container Services (SPCS)
Framework: FastAPI (Python)
Container Status: RUNNING
Endpoint Status: PUBLIC endpoint accessible

spec:
  containers:
    - name: main
      image: /my_db/my_schema/image_repository/my_img:v1
      env:
        PYTHONUNBUFFERED: "1"
        TOKEN: "changeme"
        SERVER_PORT: 8080
      resources:
        requests:
          memory: 2Gi
          cpu: 1000m
        limits:
          memory: 4Gi
          cpu: 2000m
      readinessProbe:
        port: 8080
        path: /healthz
  endpoints:
    - name: fastapi-endpoint
      port: 8080
      public: true

Expected Behavior When I send a POST request to https://my-endpoint.snowflakecomputing.app/api/data with body:

json{
    "image": "base64_image_string",
    "bill_no": "1000",
    "sheet_no": "466432",
    "attempt": "5"
}

I should get:

json{
    "status": "failed",
    "message": "Not Detected",
    "bill_no": "100017119874",
    "sheet_no": "466432",
    "crop_image_path": ""
}

Actual Behavior Instead, I'm getting a Snowflake UI HTML page (login form or default Snowflake interface) rather than my FastAPI JSON response.

Troubleshooting Done

✅ Verified service status is RUNNING
✅ Confirmed container is healthy via SHOW SERVICE CONTAINERS
✅ Verified endpoint is accessible and returns 200 status
✅ FastAPI app starts successfully (no errors in logs)
✅ Health check endpoint /healthz works correctly as I got it in logs from spsc(SELECT SYSTEM$GET_SERVICE_LOGS('my_service', '0', 'main');) but getting same html response for this also in postman
✅ Verified port 8080 is correctly configured in both container and endpoint