You can try one of these solutions:

1. Lowering the background size and slowing the animation can help minimize the visible transitions.
2. Use a gradient with colors that are closer to each other in hue and brightness. This minimizes the perceived transition between colors.
3. Use more subtle easing curves (e.g., cubic-bezier) for smoothness.
4. Adding will-change: background-position; to the body can optimize rendering and smooth out animations.