[tenebrisalietum]

- You run into copyright issues, because unless you duplicate a commercial UEFI (SMBIOS and all that good stuff) within the VM you'll be detected.

- You run into performance issues - virtualization's speed depends on paravirtualized drivers, which are readily identifiable (e.g. "virtio" disk controller). These can be emulated instead of paravirtualized but will cost performance. Windows drivers are signed so you can't just change names of things.

- Chipsets - some are often emulated by VMs. For example, if you are running a system in 2020 and are using an Intel 440BX chipset, it's probably a VM.