storage size keeps on shrinking without any activities

Recently, I am noticing on my window laptop the storage size keeps on shrinking, I am using WinDirStat to access every part of the C drive to determine where it's taking up the space most. At this point, it looks normal, I would be aware if there were activities would lead to gulping the space. Before all this, I had seen 80gb of space on C drive.

Few things I would like to point out, whether it might have to do with windows crashes; led to dumping files, windows updates,(even though I clean up after this) or even backups ( External Drive)

I would really appreciate if anyone is able to help to solve this bizzare issue

Windows Version number

• 21H2 (OSBuild 19044.2965

zebal said:

Do you mean that the available space is shrinking or the total size of a disk is shrinking?.

The available space is shrinking. I remember I had good amount of space with same settings, nothing really had been adding in that would bring it down to 15gb left.

zebal said:

You can find out which folders take up most space with:

Start -> settings -> system -> storage

Here the list is sorted, click on each item to further sort it according to use of space.

You can also try cleaning up disk space:
Open and Use Disk Cleanup in Windows 10

I have looked into the nitty and gritty of each files, however I want to identify if there were windows files that has been overriding and taking spaces.

I would like to know if installer and WinSxS folders are important in the windows directory?
I came across on clen up the WinSxS folderMS article
I have added screenshot below