Catching the computer when screen is dark, but computer still on shows just the black background and the mouse. ALT+CTRL+T changes the mouse to this, but doesn’t work for me. When the computer is sleep and off, it wakes up just fine and I can login. 
With a recent update of my Tumbleweed system several KDE/Qt packages got updated and the issue seems solved now. So far, I got no black screens. 
KDE-Plasma: 6.2.3
KDE-Frameworks: 6.7.0
Qt: 6.8.0
kernel: 6.11.6-2-default (64-bit)
1 Like
I still have this problem.
OS: Arch Linux x86_64
Kernel: Linux 6.12.1-arch1-1
Uptime: 1 day, 22 hours, 48 mins
Packages: 974 (pacman)
Shell: zsh 5.9
Display (H27T22): 2560x1440 @ 144 Hz (as 2048x1152) in 27" [External]
DE: KDE Plasma 6.2.4
WM: KWin (X11)
WM Theme: Breeze
Theme: Breeze (Light) [Qt], Breeze [GTK2/3]
Icons: WhiteSur-light [Qt], WhiteSur-light [GTK2/3/4]
Cursor: breeze (24px)
Terminal: konsole 24.8.3
CPU: 12th Gen Intel(R) Core™ i7-12700KF (20) @ 5.00 GHz
GPU: NVIDIA GeForce RTX 4060
Memory: 16.37 GiB / 62.59 GiB (26%)
Swap: 0 B / 64.00 GiB (0%)
Disk (/): 26.60 GiB / 867.01 GiB (3%) - btrfs
Local IP (eno1): 192.168.1.8/24
Locale: zh_CN.UTF-8
Just to add in January 25 I’m still having this bug. Using Arch Linux with plasma x11.
At this point it’s almost certainly 483163 – Sometimes on X11 with compositing turned on, black lock screen when using Breeze Plasma style, but controls are all there and remain interactive, like @jpetso mentioned earlier. Nothing to do but wait for it to be fixed, I’m afraid.