Hi All,
I use Docker and WSL2 frequently and have run into this problem many times. It seems to happen semi-randomly after some period of time, ~1-2 days.
I don't have a solution that addresses the core issue with Vmmem but I do have a workaround that doesn't require rebooting my whole machine. For me, going into Task Manager and ending the "Windows Subsystem for Linux" task is sufficient and Vmmem goes back to normal.
Hope this works and saves people from having to restart every time.