Why does grecaptcha return null in token?

Question

reCAPTCHA

Hello. There is such a simple code to check the operation of captcha. It turns out some nonsense in the end. In the grecaptcha.execute request, the token is returned as null. The domain for which this captcha is performed is specified in the recaptcha settings. At first I thought that the domain name was the problem, but I did 3 captchas for 3 different sites and this script always returns null. Has anyone had such a problem? Google is great, they made a service, but there is no support for it. I have no idea where to ask

<script src="https://www.google.com/recaptcha/api.js?render=site_key" ></script>
<script type="text/javascript" >
    grecaptcha.ready(function () {
        grecaptcha.execute('site_key').then(
            function (token) {
                console.log(token);
                // $('input[name="g-recaptcha-response"]').val(token);
                // console.log($('input[name="g-recaptcha-response"]').val())
            }
        );
    });
</script>