I am hitting the API by using payload and in headers giving Content-Type : 'application/json' still in browser in request headers I’m seeing Content-Type : 'text/plain'

Because of that in the backend I am getting payload in Content-Type : 'text/plain'

export const abctrigger = (payload , signal) => {
  Return fetch (API_URL, {
    method: post,
    Signal: signal
    Body: JSON.stringify(payload),
    headers: {
      Content-Type : 'application/json'
    }
  })
    .then((response) => response.text())
    .then((response) => {
      return respon se;
    })
}
 

I want to Change request headers to to Content-Type : 'application/json'