The How to Create a Custom Parameter Editor article features an example using class components. However, there is no componentDidMount method there. Changing it with useEffect hook appears to be working:
function loadScript(callback) {
    const script = document.createElement("script");
    script.src = "https://kendo.cdn.telerik.com/2025.1.227/js/kendo.all.min.js";
    script.async = true;
    script.onload = callback;
    document.body.appendChild(script);
}
React.useEffect(() => {
  loadScript(() => {});
}, [])