I recently reinstalled Antergos on one of my laptops and went with a btrfs filesystem instead of ext4 on a friend’s recommendation.
I set up my partitions like this and specifically for my issue, I gave 648gb to my /home. In total I have 750gb~ on this harddrive; an important thing to note here.
But then after my install finished, from looking in a filemanager, I saw that my /home only had 604gb.
Confirmed with lsblk here:

So I lost 44gb~ from what I gave to /home and went from 750gb~ total harddrive space to 698gb~.

Does anyone have any idea what could be the issue? I just want to know what caused the problem so that I know for when I reinstall Antergos on another laptop of mine.