Created attachment 146562 [details]
A screenshot of the graphical bug on display.

SUMMARY
When using many Aurorae themes, a vertical gradient is applied to the left and right window borders. This is most apparent on VinceLiuice's Graphite theme and its derivatives due to the thick, contrasting outlines it uses, though this is also present in other themes, like eliverlara's Nordic theme. Notably this seems to happen in themes where the bottom corners have a different shape than the top corners.

Some observations across different themes:
- When the border size is set to normal or larger, both the left and right borders are affected on Graphite and Graphite-Round
- When the size is set to Tiny, neither side border is affected on the round variations on Graphite, but the right border is still affected on normal Graphite

STEPS TO REPRODUCE
1. Apply certain Aurorae themes (most apparent with VinceLiuice's Graphite themes, but also subtly present on eliverlara's Nordic theme)
2. Open Qt program.

OBSERVED RESULT
The side window decorations have a gradient effect applied to them

EXPECTED RESULT
The side window decorations should look identical to how they look in the .svg file.

SOFTWARE/OS VERSIONS
Linux: openSUSE Tumbleweed 20220207
(available in About System)
KDE Plasma Version: 5.24.0 
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
Screen resolution is 1366x768.