https://bugs.freedesktop.org/show_bug.cgi?id=97119

--- Comment #15 from Johannes Hirte johannes.hirte@datenkhaos.de --- (In reply to Michel Dänzer from comment #14)

Which 'Tearing prevention ("vsync")' mode are you using in the kwin compositor settings? Maybe attach a screenshot of that settings page.

Was "Automatic" , but test with "Never" shows the same behavior. I've suspected glamor to be related here, but a test on Sumo with AccelMethod glamor doesn't reproduce the error.