"signature is required" error occurs always!

Relays
1

Kindly check this code below.

const { Wallet, JsonRpcProvider, id, getBytes, FetchRequest } = require('ethers');

async function send(relayUrl, body, header) {
  const req = new FetchRequest(relayUrl);
  req.setHeader('Content-Type', 'application/json');
  req.setHeader('X-Flashbots-Signature', header);
  req.body = body;
  const resp = await req.send();
  return { status: resp.statusCode, text: resp.bodyText };
}

(async () => {
  const relayUrl = 'https://relay-sepolia.flashbots.net';
  const provider = new JsonRpcProvider('https://rpc.ankr.com/eth_sepolia/.../');
  const authSigner = Wallet.createRandom();
  const txSigner = Wallet.createRandom();
  const blockNumber = await provider.getBlockNumber();

  const signedTx = await txSigner.signTransaction({
    chainId: 11155111,
    type: 2,
    to: Wallet.createRandom().address,
    value: 0n,
    nonce: 0,
    gasLimit: 21000n,
    maxFeePerGas: 20_000_000_000n,
    maxPriorityFeePerGas: 1_000_000_000n
  });

  const paramsObj = [{
    txs: [signedTx],
    blockNumber: '0x' + (blockNumber + 1).toString(16),
    stateBlockNumber: 'latest'
  }];

  const body = JSON.stringify({ method: 'eth_callBundle', params: paramsObj, id: 1, jsonrpc: '2.0' });
  const addr = await authSigner.getAddress();

  const sigA = await authSigner.signMessage(id(body)); // string "0x..."
  const sigB = await authSigner.signMessage(getBytes(id(body))); // bytes 32

  for (const [name, sig] of [['signMessage(id(body))', sigA], ['signMessage(getBytes(id(body)))', sigB]]) {
    const header = `${addr}:${sig}`;
    const { status, text } = await send(relayUrl, body, header);
    let msg = text;
    try { msg = JSON.parse(text).error?.message || text; } catch {}
    console.log(name, '->', status, msg);
  }
})().catch((e) => {
  console.error('ERR', e && e.stack ? e.stack : e);
  process.exit(1);
});

Output:

signMessage(id(body)) -> 200 signature is required
signMessage(getBytes(id(body))) -> 403 invalid flashbots signature

It worked so well, but now always facing “signature is required” error. Probably, flashbot relay has error now? Anyone knows this?