Summary: The animation for the +10 Water glow stutters when the animation loops, which suggests 1-2 extra frames in the animation.
Visual proof is attached.
Expected result: The effect rotates smoothly.
Actual result: The effect jumps backwards when the animation starts over.
Additional comments: Jumping backwards suggests extra frames in the loop or a mistimed animation duration. It is specifically the parallel arrowheads that stutter, the radial bits do not.
"New Upgrade" effect.
Edit: This is also true for the other elements (e.g. Earth).