Webhook endpoint failed to respond to our validation request

I am getting emails saying
Your webhook endpoint failed to respond to our validation request

If your webhook endpoint fails to respond to our validation requests 2 more times, we will stop sending webhooks to your webhook endpoint until you fix the issue.

am using the same method to verify the webhook which was provided in the discussion

webhook-sample/index.js at master · zoom/webhook-sample (github.com)

but still am constantly getting the same emails regarding validation failed