It seems that "Total Hard Disk Space Available" and "Largest Free Hard Disk Block" may refer to Steam game folders, but the survey appears right after the first startup without being able to configure those settings beforehand, so I guess that if I'm surveyed after setting up my Steam configuration, It will show my new repositories' space. It could say "Total Steam Folders free disk space" and "Largest free space Steam folder". So without being able to repeat the survey, I'll leave this as a misleading text label. Once again, thanks for nothing, Valve.
I can confirm this bug, Steam shows 200gb of total space even though my boot drive is 256gb and my libraries are on a 2tb and 4tb hard drives.
This is still an issue in 2024
Nothing extracted yet.
Linux Steam Hardware Survey seems to ignore any free hard disk space beyond the main root filesystem. There are Terabytes of free space in my RAID hard disks as shown in the screenshot and it fails to account for them.
I've also tried to mount them out of the /mnt/ folder and it shows the same space.