Johannes Garske put this code at the end of new request page template and replace test with something you need.

<script>
 document.addEventListener("DOMContentLoaded", function () {
    setTimeout(() => {
        // Find the target element by its name attribute
        const targetElement = document.querySelector('[name="request[anonymous_requester_email]"]');

        if (targetElement) {
            // Get the previous sibling element
            const previousElement = targetElement.previousElementSibling;

            // Check if a previous element exists and modify its text
            if (previousElement) {
                previousElement.textContent = "test";
            } else {
                console.log("No previous element found.");
            }
        } else {
            console.log("Target element not found.");
        }
    }, 400); // Delay of XYms
});

  </script>