Terraform – Upgrading AKS Kubernetes version does not upgrade node pools
If you experience during an AKS Kubernetes version upgrade that only the control plane got upgraded, you are certainly using the Terraform Azure provider in version 1.40.0 or higher.
-> https://github.com/terraform-providers/terraform-provider-azurerm/issues/5541
A current workaround is a null_resource with a trigger on the Kubernetes version and running a Bash script with the local-exec provisioner. Read more [...]