Can’t access shadowRoot

I want to pass a captcha on website https://sirus.one/#play and I need to set the solved captcha value in textarea.g-recaptcha-response -> div.innerText. TextArea has shadowRoot where website saving the response of recaptcha.

I tried to access shadowRoot like that:
document.querySelector("textarea.g-recaptcha-response").shadowRoot, but the result is null.

If I print the element in console it appears that shadowRoot exists
screenshot

How to get the shadowRoot?