Steps to reproduce: 1. On macOS, open a full-screen Safari window 2. Load https://www.space-invaders.com/world/paris/ 3. Click on the right arrow or press the right arrow key Notice more often than not a flash. This is likely an animation or compositing bug. Does not seem to happen on iOS at all, and I see it very rarely on iPad. Reproduces for me on macOS Ventura with system Safari.
There is a CSS transition for the "transform" property on the .slides-control element: <div class="slides-control" style="position: relative; height: 100%; width: 4536px; left: -1512px; transition-property: all; transition-duration: 0s; transition-timing-function: ease;">
This appears to be resolved in STP 159, going to try to find a clear point when this progressed.
I can track the progression to this range: https://github.com/WebKit/WebKit/compare/23bb0ec47b1821e3254c6ec68a38b7660042678f...85e031dc15b29db800bff87451782df542bca724 Of all those commits the fix for bug https://bugs.webkit.org/show_bug.cgi?id=244017 seems obviously the most likely to have progressed this. Marking as a dupe. *** This bug has been marked as a duplicate of bug 244017 ***