Getting the [ERR_TLS_CERT_ALRTNAME_INVALID] error when trying to do POST request

I upgraded nodejs to LTS version 12.14.1, this version has a more strict SSL control which i cannot pass when attempting to make a POST request.

The POST request:

function PostReq() {

    let chunks = [], resData = '';

    const postData = decodeURIComponent(qs.stringify({
        property1: 'value1',
        property2: 'value2'
    }));

    const options = {
        headers: {
            host: 'api.example.com',
            path: '/endpoint/base/resource',
            port: 443,
            method: 'POST',
            'Content-Type': 'application/x-www-form-urlencoded;',
            'Content-Length': Buffer.byteLength(postData),
        }
    };


    const reqPost = https.request(options, (res) => {

        res.setEncoding('utf8');
        if (res.statusCode === 200) {
            console.log('got successfull http response');
            
            res.on('data', (chunk) => {
                console.log('getting chunks...');
                chunks.push(chunk);
            });

            res.on('end', () => {
                resData = Buffer.concat(chunks).toString();
                console.log('response body data: ', resData);
            });
        } else {
            console.error('received http status code: ', res.Statuscode);
        }
    });

    reqPost.write(postData);

    reqPost.on('error', (err) => {
        console.error('HubSpot API Oauth error: ', err);
    });

    reqPost.end();
}
PostReq();

Error message:

Error [ERR_TLS_CERT_ALTNAME_INVALID]: Hostname/IP does not match certificate's altnames: Host: api.example.com. is not in the cert's altnames: mydomain.com, DNS:www.mydomain.com
    at Object.checkServerIdentity (tls.js:283:12)
    at TLSSocket.onConnectSecure (_tls_wrap.js:1331:27)
    at TLSSocket.emit (events.js:223:5)
    at TLSSocket._finishInit (_tls_wrap.js:794:8)
    at TLSWrap.ssl.onhandshakedone (_tls_wrap.js:608:12) {
  reason: "Host: api.example.com. is not in the cert's altnames: mydomain.com, DNS:www.mydomain.com"

The stack:

• nodejs
• expressjs
• nginx
• nginx proxy
• free letsencrypt ssl

Ive tried setting the NPM configuration setting ssl-strict to false but it didnt help. There is an solution that probably works, which is setting rejectUnauthorized value to false in the tls.connect() parameter but this causes serios security issues which im trying to avoid so id be grateful if anyone knows about a solution.