It depends. It depends if the decoration is stuck to the cake and cannot be removed. Or if it is a figure and we can remove it.
If it is the first case, we can’t do anything. But if it is a figure, things change.
My recommendation is that you do not put it in the fridge. There’s no need. The fondant does not require, as a general rule, a refrigerator for its conservation. So it is absurd to put it in the fridge.