My 256GB size hard-drive can put in 128TB amounts of data

I have Windows and Linux on my computer (256G) and Windows has C: System(65G) and D: Data(65G), my Linux has /(108G) and System, Data are also mounted on /.

df -h

Filesystem      Size  Used Avail Use% Mounted on
dev             3.9G     0  3.9G   0% /dev
run             3.9G  1.9M  3.9G   1% /run
/dev/nvme0n1p5  108G   39G   64G  38% /
tmpfs           3.9G     0  3.9G   0% /dev/shm
tmpfs           4.0M     0  4.0M   0% /sys/fs/cgroup
tmpfs           3.9G   68M  3.8G   2% /tmp
/dev/nvme0n1p4   65G   39G   26G  60% /Data
/dev/nvme0n1p3   65G   43G   22G  67% /System
/dev/nvme0n1p1  256M   26M  231M  11% /boot/efi
tmpfs           788M  100K  788M   1% /run/user/1000

I want to check the size of / without /System and /Data, and the Dolphin says it has 128TB:

It seems that it will show 128TB because it cannot know the size of /root and /lost+found?