SUMMARY
Hello, I seem to have a problem with changing titlebar colors with custom themes.
I use Breeze Dark as a default. I have setup a window rule to change my terminal application titlebar to a custom theme. Unfortunately, while this works fine when setting to Breeze Light for example, setting to a custom theme does not seem to change the titlebar colors.
Curiously, the background titlebar color changes eventually to the correct color, but the active titlebar text color remains unchanged still. I do not know when/how it decides to change, even restarting plasma will not change it.  
Is this some caching issue?

STEPS TO REPRODUCE
1.  Modify a default colorscheme and set a different Active/Inactive Titlebar Color.
2.  Save and then change the system color to that colorscheme.

OBSERVED RESULT
Titlebar will still remain the same color. After some time it seems that the background color works but the Text color still remains incorrect.

EXPECTED RESULT
The titlebar switches to the correct colors.

SOFTWARE/OS VERSIONS
Linux: Arch Linux, kernel: 5.14.16-arch1-1 (64 bit)
KDE Plasma Version: 5.23.3
KDE Frameworks Version: 5.88.0
Qt Version: 5.12.2