See attached screenshot. I got it to reproduce a few times, every time it was with Skype. Reproducible: Sometimes
Created attachment 94048 [details] Screenshot
Likely related to something™ skype does in reaction to some™ action, eg. maybe un/maximizing? Does explicit "glx" mean you cannot reproduce it with EGL? Is always (only) the right boder affected?
It looks like one part of the Aurorae theme not being updated at all. Which is kind of weird as the architecture should ensure that it either works always or never.
We fixed a similar bug which I just cannot find. I assume the issue is fixed in latest release (e.g. 5.10), if not please reopen.