Capture Query String & send as hidden fields

<script>
    (function () {
        // Uncomment below line to show the hidden fields for debugging
        // document.querySelector('input[name="field[9]"').type = 'text';
        // document.querySelector('input[name="field[11]"').type = 'text';

        // Below would capture the query strings from the cookie
        var url = new URL({{cookie - __gtm_campaign_url}}),
            params = new URLSearchParams(url.search),
            utmSource = params.get('utm_source'),
            utmMedium = params.get('utm_medium'),
            fbclid = params.get('fbclid'),
            gclid = params.get('gclid');

        // Fill the hidden fields with the required query params
        // Change the selector or the variable name to send the required query params
        document.querySelector('input[name="field[9]"').value = utmSource;
        document.querySelector('input[name="field[11]"').value = fbclid;

        // Uncomment if you want to grab either FBCLID or GCLID & change the selector accordingly
        // document.querySelector('input[name="field[11]"').value = gclid || fbclid;
    })();
</script>