Gen 2 VM SKUs are now generally available for Windows on AKS. Azure Generation 2 (Gen2) virtual machines (VMs) support key features not supported in generation 1 VMs (Gen1). This enables you to bring Windows workloads to the cloud native platform more easily.
Key features for Gen 2 VMs include increased memory, Intel Software Guard Extensions (Intel SGX), and virtualized persistent memory (vPMEM). Generation 2 VMs use the new UEFI-based boot architecture rather than the BIOS-based architecture used by generation 1 VMs.
Only specific SKUs and sizes support Gen2 VMs. Check the list of supported sizes, to see if your SKU supports or requires Gen2. Gen2 VMs on Windows are supported for WS2022 only.