SUMMARY

System Monitor reports a wrong amount of total available disk space. It says that I have 2,0 TiB of total space when I only have two drives of 1 TB + 256 GB. 

STEPS TO REPRODUCE
1. Open System Monitor.
2. See the Disk card with the total available space.

OBSERVED RESULT
It shows that I have 2 TiB of total space.

EXPECTED RESULT
It shows that I have around 1,2-1,3 TiB of total space.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.0.4
KDE Frameworks Version: 6.1.0
Qt Version: 6.7.0
Kernel Version: 6.8.9-arch1-2 (64-bit)

ADDITIONAL INFORMATION

df -h (loop devices removed for clarity)

S.ficheros                    Tamaño Usados  Disp Uso% Montado en
/dev/mapper/vg--root-lv--root   684G    86G  598G  13% /
devtmpfs                        4,0M      0  4,0M   0% /dev
tmpfs                            16G    41M   16G   1% /dev/shm
efivarfs                        128K    51K   73K  42% /sys/firmware/efi/efivars
tmpfs                           6,2G   9,8M  6,2G   1% /run
tmpfs                            16G    13M   16G   1% /tmp
/dev/nvme0n1p2                 1022M   183M  840M  18% /boot
/dev/mapper/home                230G   109G  120G  48% /home
tmpfs                           3,1G    68K  3,1G   1% /run/user/1000

lsblk (loop devices removed for clarity)

NAME                    MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINTS
nvme0n1                 259:0    0 931,5G  0 disk  
├─nvme0n1p1             259:1    0   230G  0 part  
│ └─md127                 9:127  0 229,9G  0 raid1 
│   └─home              254:3    0 229,9G  0 crypt /home
├─nvme0n1p2             259:2    0     1G  0 part  /boot
└─nvme0n1p3             259:3    0   700G  0 part  
  └─root                254:0    0   700G  0 crypt 
    ├─vg--root-lv--swap 254:1    0    16G  0 lvm   [SWAP]
    └─vg--root-lv--root 254:2    0   684G  0 lvm   /
nvme1n1                 259:4    0 232,9G  0 disk  
└─nvme1n1p1             259:5    0   230G  0 part  
  └─md127                 9:127  0 229,9G  0 raid1 
    └─home              254:3    0 229,9G  0 crypt /home