`options._diff` not called for implicit Fragments

import { render, h,options, Fragment}  from "preact"
import renderToString from "preact-render-to-string"

const oldDiff = options.__b;
options.__b = (vnode) => {
  if (vnode.type === Fragment) {
    console.log(vnode.type === Fragment ? vnode.props:null)
  }
  if (oldDiff) oldDiff(vnode)
}

function App() {
  return <div>
    <h1>test</h1>
    {[
      <p key="1">1</p>,
      <p key="2">2</p>,
      <p key="3">3</p>,
    ]}
  </div>
}

const app = document.getElementById("app");
render(<App />, app)

console.log("=====")

// Fragments not visible in options._diff with RTS
renderToString(<App />);

Start by running the JSX reproduction comparing client render with renderToString and observe whether options.__b receives implicit Fragment vnodes. Trace the renderToString path and its Fragment handling; done when implicit Fragments trigger the expected hook consistently with client rendering.