Normally I would consider this a bug. However over the years I’ve come to the conclusion that Windows is a pretty toy. It works wonderfully “in the small”. But it isn’t useful for significant programmer workloads (like typing :-) ).
Source: WSL Isn’t Linux | Hacker News
Your mistake was considering Windows suitable for anything but media consumption. It will phone home, it will reboot when it feels like it, and it won’t resume state when it does reboot or resume from sleep.
The best use for WSL is to use it to shell into a proper Linux host. Only way you can guarantee you won’t lose your work when the OS decides to do something.