Updating istio configuration does not update cloud load balancer

I have installed Istio by following the https://istio.io/docs/setup/install/helm/#option-1-install-with-helm-via-helm-template instructions and using a values.yaml to configure istio components, in particular configuring an AWS public NLB for istio ingress gateway.
As a result, an public NLB was created in AWS.
But then, I wanted to change the configuration to make the NLB private. So I changed my values.yaml to indicate the new options for the ingress gateway section, and apply the manifests again.
Is it normal that the k8s object has been changed but not the AWS load balancer ?
Is it possible to force the update of the cloud load balancer when updating istio ingress configuration ?
(other than manually delete the NLB and re-applying the istio manifests)
Thank you