Windows Subsystem for Linux (WSL) which lets you basically run linux kernel along side the windows kernel which lets you do a lot of cool stuff like containers, linux apps, whole DEs, etc.
It was pretty cool for like 5 minutes until people realized that keeping windows around was kind of pointless and we should just be running pure linux lol.
It’s still a good feature, but it just gives you a direct comparison of linux vs windows which tends to outshine windows.