{invalid_client} for web sign in, but works for apps sign in

We are finding issues with SIWA on web, but looks fine for the apps.

• Able to authenticate with Apple ID and get a successful response for both web and apps.
• The user verification step fails for web when the call is made with the auth code. We are receiving

{invalid_client}. The only change we can see for web is, we pass the service id as the client id param.

The error response is not leading us anywhere. Could someone help us find what is wrong here?

Thanks

Vinny