Smart Animate suddenly causes dark/gray artifacts behind semi-transparent gradient fills

Issue

Smart Animate has suddenly started producing a dark/gray visual artifact behind layers that use semi-transparent gradient fills during the transition.

I have been working on the same Figma file and the same component for the past four days. The prototype animation was working correctly until a few hours ago. I did not make any changes to the component structure or animation setup that would explain this behavior. The issue occurs both in the Figma Desktop app and in the browser.

What happens

The component uses Smart Animate with a Custom Bezier easing. During the Smart Animate transition, layers containing gradient fills with reduced opacity appear to reveal a dark/gray background or compositing layer behind them. It looks as if a dark surface is temporarily being rendered behind the semi-transparent fill during the animation.

The darkening does not appear as an overlay on top of the entire component. It specifically appears behind the transparent/semi-transparent areas of the gradient during the transition. This makes the effect look like a rendering/compositing issue rather than an intended opacity interpolation.

Tests I performed

I tested the same interaction with Dissolve instead of Smart Animate, and the dark/gray artifact does not occur. I also removed the gradient fill from the affected layer. After removing the gradient, the visible gray artifact appears to disappear, although it is difficult to determine with complete certainty because the underlying surface is opaque. This strongly suggests that the issue is related to the way Smart Animate currently renders/interpolates semi-transparent gradient fills.

The gradient and its changing opacity are intentional parts of the component’s visual design and animation. Removing the gradient or replacing the animation with Dissolve is therefore not a viable solution. I am also sharing a prototype video that shows both the Smart Animate and Dissolve version.