Created attachment 165332 [details]
Screenshot of System Monitor Overview

SUMMARY
The Plasma System Monitor reports twice as much disk as actually available.  When I look in the System Monitor on a laptop that only has a single 256GB disk, it shows that there is 476.3GiB total space (see attached image).  This may actually be a problem in the underying kstatsviewer/ksystemstats as I also see odd looking numbers there, but I'm not certain how to interpret them.

crd@fedora:~$ lsblk -o+MODEL,SIZE
NAME                                   MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINTS MODEL                       SIZE
sda                                      8:0    0 238.5G  0 disk              SK hynix SC308 SATA 256GB 238.5G
├─sda1                                   8:1    0   600M  0 part  /boot/efi                               600M
├─sda2                                   8:2    0     1G  0 part  /boot                                     1G
└─sda3                                   8:3    0 236.9G  0 part                                        236.9G
  └─luks-d1534652-aa68-47b8-aa5a-dc287aecba1b
                                       253:0    0 236.9G  0 crypt /home                                 236.9G
                                                                  /                                     
zram0                                  252:0    0     8G  0 disk  [SWAP]                                    8G
crd@fedora:~$ rpm -qi ksystemstats 
Name        : ksystemstats
Version     : 5.92.0
Release     : 1.fc40
Architecture: x86_64
Install Date: Thu 25 Jan 2024 04:35:20 AM EST
Group       : Unspecified
Size        : 1292525
License     : BSD-2-Clause AND BSD-3-Clause AND CC0-1.0 AND GPL-2.0-only AND GPL-3.0-only AND LicenseRef-KDE-Accepted-GPL
Signature   : RSA/SHA256, Sat 13 Jan 2024 02:59:25 PM EST, Key ID 0727707ea15b79cc
Source RPM  : ksystemstats-5.92.0-1.fc40.src.rpm
Build Date  : Thu 11 Jan 2024 04:29:40 AM EST
Build Host  : buildvm-x86-19.iad2.fedoraproject.org
Packager    : Fedora Project
Vendor      : Fedora Project
URL         : https://invent.kde.org/plasma/ksystemstats
Bug URL     : https://bugz.fedoraproject.org/ksystemstats
Summary     : KSystemStats is a daemon that collects statistics about the running system.
Description :
KSystemStats is a daemon that collects statistics about the running system.

STEPS TO REPRODUCE
1. Install Fedora KDE Live nightly ISO
2. Open System Monitor to the Overview page
3. Observe that the total disk space is overreported by 100%

OBSERVED RESULT
System Monitor reports 476.3GiB Total Space

EXPECTED RESULT
System Monitor should report 238.5GiB Total Space

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 6.0 RC1
(available in About System)
KDE Plasma Version: 5.92.0
KDE Frameworks Version: 5.248.0
Qt Version: 6.6.1

ADDITIONAL INFORMATION
I don't see the same behavior on Fedora 39 with the stable version of KDE.