It would be much more useful if you could save / restore checkpoints. And because it gets wiped on every reboot it means you can never test software that needs to restart the machine (to install services and whatnot).
> Note, however, that as of Windows 11 Build 22509, your data will persist through a restart initiated from inside the virtualized environment—useful for installing applications that require the OS to reboot.
They specially call out that files are retained during a reboot of the sandbox to allow for the “restart required” condition