Please correct me if I am wrong, but you have specified AWS API Gateway as your kintone webhook URL.
However, the webhook failed to send, and a 403 error occurred?
I'm assuming that you are checking the kintone audit log for the relevant information.
In that case, there is a possibility that an error occurred due to the inability to access the corresponding URL.
However, the configuration of the webhook destination, including the API Gateway, is not supported, so it would be better to check with the provider such as AWS.