Failed to Fetch Error while calling Azure Function

I am calling an Azure Function which is publicly accessible from my SPFx web part.

It is a POST Request and I am getting a Failed to Fetch error.

The same API call is working fine if I execute it from POSTMAN.

Below is the code.

fetch(checkSubscriptionURL, {
          method: "POST",
          body: JSON.stringify({ "TenantID": tenantId }),
          headers: {
            "Content-type": "application/json",
            "Accept": "application/json"
          }
        }).then((res) => {
          console.log(res);
          if (res.status !== 200) {
            reject();
          }
          else {
            res.json().then(data => {
              if (data && data.length > 0) {
                resolve(this.parseSubscription(data[0]));
              }
              else {
                reject();
              }
            })
          }
        }).catch((e) => {
          console.log(e);
          reject();
        })

Can anyone please help with this?

I tried to make the call with SPFxHTTPClient but getting the same error with that as well.

Thanks in advance.