I compressed my PC's Windows 10 C drive after spending a very long time trying to figure out how to get it out of the "red". Unfortunately, the next time I started up LTS Ubuntu, it complained about the virtual disk being compressed and would not start up.
I followed other web advice to look under C:\users\[me]\AppData\Local\Packages
There I found something named CanonicalGroupLimited.Ubuntu20.04onWindows_79rblahblah ..
After I decompressed that package LTS Ubuntu worked again.
