Should I do additional verification with react-google-recaptcha library?

Question

I have implemented Google's ReCaptcha in React using the react-google-recaptcha library. I use the component like this:

    <ReCAPTCHA
       sitekey={captchaSiteKey}
       ref={captchaRef}
       onChange={handleVerification}
    />

According to the documentation the onChange method is called when the verification is successfull, but only userverify api is called and the server key is not used at all. Should I additionally check the token and call the siteverify api as stated in Google's documentation (https://www.google.com/recaptcha/api/siteverify)?

I tried verifying the token in the onChange method but siteverify always returns empty response.

    const response = await fetch(`https://www.google.com/recaptcha/api/siteverify`, {
        method: 'post',
        mode: 'no-cors',
        headers: {
            Accept: 'application/json',
            'Content-Type': 'application/json',
        },
        body: JSON.stringify({
            secret: RECAPTCHA_SERVER_KEY,
            response: token,
        }),
    })

Should I do this at all, or the verification from ReCAPTCHA component is enough?