Unfortunately I couldn't recreate the bug in a CodePen.
So I made a screencast.
The bug occurs on Chrome Android. iOS Safari is okay– The screencast is from a browserstack emulation with the exact same issue.
The issue occurs when I start tweening x or y WHILE CLIP-PATH is still tweening.
As soon as I get rid of x and y tweens, the flicker is gone!
// Rough html layout