bad request response to fetch REST API : I have built an API and app that uses that API. When I POST method via Postman it works fine but when I try fetch via app I get bad request 400 status response. What am I doing wrong?

here is my js code:

    const myForm = document.getElementById('loginForm');
    
    myForm.addEventListener('submit', function(e) {
      e.preventDefault();
        
        const url = 'https://thawing-peak-69345.herokuapp.com/api/auth';
    
        const myHeaders = new Headers();
        myHeaders.append('Accept', 'application/json, text/html, */* ');
        myHeaders.append( 'Content-Type', 'application/json, charset=utf-8')
    
      
       
     const formData = {
       email: this.email.value,
       password: this.password.value
       };
       
        
        console.log(formData);
    
        const fetchOptions = {
          method: 'POST',
          mode: 'no-cors',
          cache: 'no-cache',
          headers: myHeaders,
          body: JSON.stringify(formData)
        };
        
        fetch(url, fetchOptions)
          .then(res => res.json())
          .then(res => console.log(res))
          .catch(err => console.log(err)) 
      
        })

  [request photo[\]\[1\][1]


and response
[enter image description here][2]


headers request:
[enter image description here][3]

headers response:
[enter image description here][4]


  [1]: https://i.stack.imgur.com/LKso7.png
  [2]: https://i.stack.imgur.com/vQVnm.png
  [3]: https://i.stack.imgur.com/yDCsk.png
  [4]: https://i.stack.imgur.com/1RS0j.png