103 Early hints response not sending properly with HTTP/2 request

Question

I have implemented simple proxy server with using node js. So the proxy will send Early hints response once it receives the request, it works well for HTTP/1.1 request but when I try with HTTP/2 request, it doesn't send the Early hints. I need to handle HTTP/2 Early hints because most of browsers are only accepting HTTP/2 or over Early Hints, not HTTP/1.1 Early hints. Please help me with how to fix this issue.

const http2 = require("http2");
const fs = require("fs");
const proxy = require("http2-proxy");

const options = {
  key: fs.readFileSync("./key.pem"),
  cert: fs.readFileSync("./cert.pem"),
  passphrase: "password",
  allowHTTP1: true,
};
const server = http2.createSecureServer(options, (req, res) => {
  console.log("Hello", req.httpVersion);
  res.writeEarlyHints(
    {
      link: ["</_next/static/css/11031e50f5a9bdb7.css>; rel=preload; as=style"],
    },
    () => {
      console.log("Early Hints sent");
    }
  );
  
  proxy.web(req, res, {
    hostname: "mantine.dev",
    protocol: "https",
  });
});
server.listen(5000);

I tried to log for early hints and noticed that the callback function of writeEarlyHints is not executing in case of only HTTP/2 request.