Massive change in Windows size

[Acadia]

Good Grief!! My Windows installation DECREASED in size by 20gig between yesterday and today. I did not uninstall anything and did no cleanup. Anyone else notice any huge decreases?
Acadia

 

[lokamoka820]

If your installation had a windows.old folder, it would be deleted automatically after 10 days, as it contains your previous Windows installation. Considering that Windows 26H2 is currently rolling out, it’s possible that your 25H2 version was removed automatically.