Gemini Dynamic Webhooks Signature verification not working as per docs

Gemini API
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1 
import { GoogleGenAI } from "@google/genai";
import express from "express";
import jwt from "jsonwebtoken";
import jwksClient from "jwks-rsa";

const app = express();
app.use(express.text({ type: 'application/json' }));

const client = jwksClient({
  jwksUri: "https://generativelanguage.googleapis.com/.well-known/jwks.json"
});

function getKey(header, callback) {
  client.getSigningKey(header.kid, (err, key) => {
    const signingKey = key.getPublicKey();
    callback(null, signingKey);
  });
}

app.post('/gemini-webhook-dynamic', (req, res) => {
  const token = req.headers['webhook-signature'];

  if (!token) {
    return res.status(400).json({ error: "No signature header" });
  }

  jwt.verify(
    token,
    getKey,
    {
      algorithms: ["RS256"],
      audience: "your-configured-audience"
    },
    (err, decoded) => {
      if (err) {
        return res.status(400).json({ error: "Invalid Dynamic signature", details: err.message });
      }

      console.log("Verified Dynamic payload success.");
      res.status(200).json({ status: "received" });
    }
  );
});

i’m following above docs to verify webhook signature, but on verify i get Malfarmed token error.
also from where do we get the “audience” value used in the verification step?