As others mention, the versioning scheme is confusing. I'd like to add that I found even the name confusing, as I initially thought that this would allow some parts of Windows to run on Linux.
"Linux Subsystem for Windows" would have made a lot more sense to me.
Actually WSL doesn't contain any Linux at all because "Linux" originally refers to the Linux Kernel and usually GNU/Linux refers to a system using Linux as a kernel but GNU software for the userspace. So, the Name should rather have been something like "Windows Subsystem for Posix Programs" which doesn't quite sound so good.
This was true for WSL1, but WSL2 does contain a Linux kernel. The source code for it is available at: