Hi Stefan Kiessig,
Thanks for patience while reviewing your thread.!
I found the one document related to this why it will be creating the second resource group
The AKS creates a second resource group to automatically manage the virtual machines, network, and storage needed to run your Kubernetes cluster. This keeps everything organized and makes it easier for AKS to maintain the underlying infrastructure
Please refer below content in documentation
Why are two resource groups created with AKS?
AKS builds upon many Azure infrastructure resources, including Virtual Machine Scale Sets, virtual networks, and managed disks. These integrations enable you to apply many of the core capabilities of the Azure platform within the managed Kubernetes environment provided by AKS. For example, most Azure virtual machine types can be used directly with AKS and Azure Reservations can be used to receive discounts on those resources automatically.
To enable this architecture, each AKS deployment spans two resource groups:
- You create the first resource group. This group contains only the Kubernetes service resource. The AKS resource provider automatically creates the second resource group during deployment. An example of the second resource group is MC_myResourceGroup_myAKSCluster_eastus. For information on how to specify the name of this second resource group, see the next section.
- The second resource group, known as the node resource group, contains all of the infrastructure resources associated with the cluster. These resources include the Kubernetes node VMs, virtual networking, and storage. By default, the node resource group has a name like MC_myResourceGroup_myAKSCluster_eastus. AKS automatically deletes the node resource group whenever you delete the cluster. You should only use this resource group for resources that share the cluster's lifecycle.
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