virtualbox – Oracle Virtual Box Linux VM : virtual size vs actual size

I’ve just installed a fresh Kali version on Oracle Virtual Box.
To do so, I created a VM with 250Gb disk space, then ran the .iso : hence, the .vdi file size is 250Gb.
But when logged in, when I try – let’s say – to unrar a file, the system claims that I don’t have enough free space.

I checked in Virtual Box interface, and my actual and virtual sizes are almost the same : 250 Gb.

Besides, gparted shows a 250Gb allocated space (almost no free space).

Here you can see the result of lsblk.

And here you can see df -h result.

213Gb seem to be available (however, they are not shown in gparted !!)

During the Kali installation, I chose the disk encryption option (and the installer took a long time to write arbitrary bytes to prevent meta data leaks). But I remember having done this before, without having the problem I’m experiencing right now.

How can I get my space back ?

Any help appreciated !