Why is the contents of the Windows folder in Win10 half the size of the folder itself?

Question

Windows

Tell me, what could be the reason for such a huge difference when calculating the number of occupied space?
On the left - the size of the Windows folder, on the right - the size of all its contents (most likely, not all, because the number of files does not converge). The display of hidden folders is enabled, WinSxS takes about 6 GB, which is not critical and is included in the considered content.
The disk cleanup built into windows does not help, there are no such huge numbers anywhere else.

Answer 1

Everything turned out to be quite simple: not all hidden folders are shown by windows without a checkmark "Hide protected operating system files". I checked the TreeSize prog disk, it turned out this: there is a Windows / Installer folder, where there is just a sea of ​​\u200b\u200bsome 17 GB installers. For example, I found there:
1) some update for the office (800 mb), if you run it and then cancel it, it creates a file of the same size here and does not delete it after itself
2) Xamarin for VS installer (340 mb), Why the hell do I need it if I already installed it?
3) three packages of modules for RealSense (total 900 mb), the same question. Interestingly, these packages are included in a single RealSense installer, i.e. I didn’t download them separately (updates on them also don’t come by themselves). Those. when installed from a single package, they were unpacked here, installed, and then left here.
4) installers for Project and Outlook (in total 400+ mb), which I did not install and did not intend to
5) some packages for the office, more than 20 pieces, more than 150-200 mb each
IMHO, the game is complete. I don't see the point in keeping it all. In my opinion, this place is in the Temp folder.

Answer 2

The rest is compromising evidence on you, it’s not good to show this =)

Answer 3

I don’t even know if you seem to have a local problem or not everything hidden was taken into account