Check what is the output: (Read only)
$ journalctl --no-pager -p 4 | grep 'BTRFS'
and
$ sudo btrfs device stats /
and
$ sudo btrfs scrub status /
You got the corrupted swapfile. I think RAM is probably damaged.
After full backup, take out all RAM from your mainboard and test each individual RAM with mprime or memtest to see which one is faulty.
If all RAM are fine, your disk or mainboard (bus system) is probably faulty.
If you need a automatic Btrfs notification, you can install btrfs-desktop-notification-git from AUR ( it was created by me). It notifies you immediately to easily notice when any error/warning Btrfs message appears.