Issue with Webhook Secret and Authentication Mechanism

I have configured a webhook for an alert and was able to pass a secret while setting it up. However, I am receiving the webhook API calls even without the secret being validated, and I am unable to see the secret anywhere in the request headers or body.

Could you clarify where the secret is being passed, or if there's a specific way to verify it within the request?

Additionally, is there any way to authenticate the webhook request using client credentials, similar to how client credential-based authentication works in other APIs?