drawing artifacts with Anonymous Pro

on linux/x11, Anonymous Pro (Anonymous Pro Minus to be exact) has drawing artifacts (as shown in the attached screenshot). i've experienced issues with this font for quite some time already, so it's not necessarily a regression.

observations:

• only linux is affected, windows/macos seem to work fine
• only qt/kde applications seem to be affected (other frameworks can deal with the font)
• i've been able to reproduce this on several computers
• it mainly seems to be triggered by scrolling (while the scrolling direction doesn't matter