Created attachment 146560 [details]
A screencap of system settings with funky text elements

SUMMARY

Unsure when this started codebase-wise, but on Plasma 5.23.5 and now 5.24.0 (the only variants I've tried recently, I literally just got back onto Plasma the other day) I'm seeing some visual glitching of text elements on various things within Plasma as I scroll through. Most notably, within systemsettings on pages with a lot of scrolling entries - Color Schemes, Desktop Effects, etc. I've seen a number of bugs referencing this in the past, with much more severe glitches, which were resolved by upstream Mesa changes. This could be related, or a continuation of the same problem. This is really more of a papercut than anything - the system is still perfectly usable, and the text will render normally after scrolling a bit.

Disabling compositing does not affect this behavior. Most other apps, both Qt and GTK appear to be just fine. It's only within system settings and some other Plasma core stuff such as Discover.

My system is running an AMD Ryzen 4750U, with integrated Vega graphics, on the standard Mesa / X11 shipped with latest Arch packages.

STEPS TO REPRODUCE
1. Open system settings
2. Navigate to a page with a lot of scrolling elements (such as Workspace Behavior > Desktop Effects)
3. Scroll around

OBSERVED RESULT

Text elements may begin normal, but after some scrolling are rendered incorrectly - only parts of characters will appear. The text will go in and out of this state if I scroll further.

EXPECTED RESULT

Fully readable text.

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Arch, X11, kernel 5.16.8-arch1-1, Mesa 21.3.5-1
KDE Plasma Version: 5.24.0 (also appeared on 5.23.5)
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION

On further inspection, this appears to also affect certain other UI elements like nearby checkboxes. This is visible in the bottom half of the attached screencap.