const res3 = await fetch(url2, {
      method: "GET",
      header: {
        Accept: "application/json",
        "Content-Type": "application/json",
      },
    })
    .then((response) => response.json())
    .then((data) => {
       console.log("Success:", data);
     })
    .catch((err) => console.log("thown error-->" + err));
    
    console.log(res3);
     const response=await res3.json() //erroneous line
    console.log(response);
    

here res3 = undefined is printed

and when the below code is executed

 const res3 = await fetch(url2, {
          method: "GET",
          header: {
            Accept: "application/json",
            "Content-Type": "application/json",
          },
        });
        
    const response=await res3.json()
    console.log(response);

response = [object , Object] is printed on console

and when try to access the response as response.obj where the backend sends back the response as: res.json({ obj:data, msg:"Success" })