It seems like they are subvolumes. How did you install the system?
When mounting a btrfs without any options root/main directory is containg subvolumes. Meaning that when creating a directory it is being created as subvolume, then in that subvolume there are regular files.
What does the btrfs subvolume list / say?
Also as side note, there is nothing wrong with updating on GUI.
Right, got it, create-fstab automatically creates subvolumes for /var/cache and /var/log on btrfs.
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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
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