Created attachment 134197 [details] Example screenshot SUMMARY See the attachment. The horizontal separator lines slightly bleed outside the bounds of their containing widget. Visible in the desktop right-click menu, or in menu dropdowns. Curiously, disabling compositing makes the issue go away. SOFTWARE/OS VERSIONS KDE Neon KDE Plasma Version: 5.20.4 KDE Frameworks Version: 5.77.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION I think a relatively recent regression. The issue started occurring for me after one of the updates around October or November.
*** This bug has been marked as a duplicate of bug 428095 ***