Created attachment 159047 [details]
Screenshot for section OBSERVED RESULT

SUMMARY
When a user changes a setting in System Settings to a value that isn't a default, the UI element controlling the value usually gets highlighted.  This doesn't happen to UI elements in "System Administration > Software Update"


STEPS TO REPRODUCE
1. Open System Settings
2. Navigate to "System Administration > Software Update"
3. If available, click on "Defaults"
4. If enabled, click on "Apply"
5. Change any one setting:
   - radio buttons "Manually"/"Automatically" for "Update software" 
   - dropdown (aka combobox) "Update frequency"
   - checkbox "Use offline updates"

OBSERVED RESULT
After step 5 all UI elements remain "unhighlighted". See the first screenshot.


EXPECTED RESULT
The UI element being changed to a non-default value has a highlight. See the second screenshot – the panel "System Settings > Workspace > Window Management > Tasks Switcher > Main" is shown with examples of both default and non-default values.


SOFTWARE/OS VERSIONS
Operating System: KDE neon 5.27
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.106.0
Qt Version: 5.15.9
Kernel Version: 5.19.0-41-generic (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i5-8250U CPU @ 1.60GHz
Memory: 7.7 GiB of RAM
Graphics Processor: Mesa Intel® UHD Graphics 620
Manufacturer: Dell Inc.
Product Name: Inspiron 5570

ADDITIONAL INFORMATION
In my color scheme, the UI elements with default values happen to have the blue highlight, and UI elements with non-default values – orange highlight.