Nothing is wrong. Its just that the folder you need info has
multiple files or folders inside it, and as you can see on your screenshot
there is no info about folder size on your windows explorer window too.
2022-02-07_204823.png
So you have to get sizes of all files and folders inside it, just like when
you right click on folder icon and select "properties" which will actually
calculate the folder size.
Easiest way is to use CMD or PowerShell, you can read more >>>
https://stackoverflow.com/questions/12813826/get-folder-size-from-windows-command-line
Or you can use some node modules that handles file system.