Created attachment 167376 [details]
A screenshot of the CPU usage graph, showing coloured vertical lines being drawn around the graph data

SUMMARY
When viewing the History page of System Monitor, the default CPU graph contains visual artifacts that look like vertical bars of opaque and semi-transparent pixels that match the colors assigned to the CPU cores being displayed.

STEPS TO REPRODUCE
1. Open the System Monitor app
2. Switch to the History tab in the app's default configuration, or otherwise view the CPU graph

OBSERVED RESULT
Colored lines that aren't part of the main graph's data appear on top of the graph.

EXPECTED RESULT
The graph data would be visible without any extra visual artifacts

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.0.2
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2
Kernel Version: 6.8.1-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 8 × 12th Gen Intel® Core™ i3-12100
Memory: 15.4 GiB of RAM
Graphics Processor: Mesa Intel® UHD Graphics 730
Manufacturer: Micro-Star International Co., Ltd.
Product Name: MS-7D46
System Version: 1.0

ADDITIONAL INFORMATION
* I noticed this when I first updated to KDE 6 (which would correspond to v6.0.1)
* This seems similar to Bug 434462, although the exact visual effect is different in this case, and only a specific graph is affected
* I'm using integrated graphics on an Alder Lake CPU, and have not changed drivers from the default