Folder properties box mistakes "used" for "free" space percentage

For exemple, for my /home directory, the properties box reports

Size: 38051 items, totalling 32.6 GiB (34,957,716,367 bytes) Usage: 147.7 GiB of 190.1 GiB free (22% used)

Of course, 147.7 used out of 190.1 total means that 42.4 GiB remain available, or in other words, 78% are used and 22% are free.

This caption should rather read something like

Usage: 147.7 GiB out of 190.1 (22% free)

On the other hand,df /dev/sda4says

Filesystem     1K-blocks     Used Available Use% Mounted on
/dev/sda4      199301464 34202132 154902548  19% /home