SUMMARY

I hope this is the right product and component, I'm not sure! But the setting appears to be saved in kwinrc so I assume this is a kwin bug. It wasn't easy to figure out where to report this, so if it is wrong, please move it to the proper location.


STEPS TO REPRODUCE
1. Set the locale for numeric values to one that uses comma (such as Swedish: sv_SE.UTF-8)
2. Log out and back in again for the change to take effect
3. In system settings, go to "Display and Monitor" -> "Night Colour"
4. For "Activation time" select "Sunset to sunrise at manual location".
5. Try to enter values with decimals. Only the locale appropriate separator is possible to enter.
6. Click apply to save.
7. Close the settings and reopen. Note that every digit after the decimal separator has been silently discarded!

This works properly if using a locale that has period as the decimal separator such as C.UTF-8

OBSERVED RESULT
Digits after decimal separator are discarded.

EXPECTED RESULT
Digits after decimal separator should NOT be discarded.

This works properly if using a locale that has period as the decimal separator such as C.UTF-8.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma:
(available in About System)
KDE Plasma Version:  5.24.5
KDE Frameworks Version: 5.94.0
Qt Version: 5.15.4
Graphics Platform: X11

ADDITIONAL INFORMATION