SUMMARY
Screen dimming is only applied to laptop display, not connected external displays in Wayland, works in X11


STEPS TO REPRODUCE
1. In Settings - Energy Saving:
  Set Dim Screen after 1 minute
  Set Screen Energy Saving - switch off after 2 minutes
2. Wait 1 minute

OBSERVED RESULT
Only the laptop screen dims after one minute, monitors are at full brightness
All screens sleep at 2 minutes.

EXPECTED RESULT
All screens dim at the configured time and sleep at the configured time

SOFTWARE/OS VERSIONS
Operating System: Linux - Solus 4.3
KDE Plasma Version: 5.27.4
KDE Frameworks Version: 5.105.0
Qt Version: 5.15.9
Kernel Version: 6.2.14-232.current (64-bit)
Graphics Platform: Wayland
Processors: 16 × 11th Gen Intel® Core™ i7-11800H @ 2.30GHz
Memory: 62.5 GiB of RAM
Graphics Processor: Mesa Intel® UHD Graphics
Manufacturer: Dell Inc.
Product Name: XPS 17 9710

ADDITIONAL INFORMATION
Screen dimming works as expected with X11

Setup: Laptop connected to 2 external displays using a Thunderbolt dock. One is DisplayPort, the other HDMI
The DisplayPort display is set as Primary

Powerdevil is running

```
❯ pgrep -fla powerdevil
1288 /usr/lib64/kf5/org_kde_powerdevil
```

There's nothing from powerdevil in journalctl --since=-5m output, or any errors.

I searched for other bugs, but didn't find anything that seemed to describe this.
This is different from https://bugs.kde.org/show_bug.cgi?id=462695 in that all displays are being put to sleep, but only the laptop display is being dimmed.