Windows says my installed apps are using about 114 GB, but when I add up the sizes shown for the individual apps, I only get roughly 65–75 GB. Could Windows be counting apps or files that aren't displayed in the installed-apps list? Most of my apps have shortcuts on the desktop—could those be counted twice, or is the space coming from other locations?
2 Answers
The total can include more than the main program folder: application data, dependencies, caches, updates, DLC, and launcher files may be stored elsewhere, such as ProgramData or your user AppData folders. Microsoft Store and Xbox-style installations can also be reported inconsistently. Desktop icons are normally just shortcuts and do not duplicate the installed application or take up significant space.
Windows' installed-app storage estimate is notoriously unreliable. It often depends on apps reporting their own sizes, and many programs either report incomplete information or leave out related files. For a more accurate breakdown, use a disk analyzer such as WizTree or TreeSize to inspect which folders are actually using the space.

Thanks, I'll try TreeSize. I think I've heard of it before.