Different reflections in animation

[^Lele^]

Neither.
There's pollution from the stochastic opacity, somehow.

[kosso_olli]

Oh, okay. So the issue is affecting refractions in still images as well?

[caypiranha]

Which of the results is the correct one? Frame 1 or 30? Or none of them?

You may find out while rendering a frame with "normal" and then compare it - that one should win - if I am not mistaken.