When a open CollapsingHeader is dragged in a dnd the dragged CollapsingHeader is shown in a closed state, but uses the open size. Then when you release the CollapsingHeader, during the return animation, the closed size is used. Finally when the animation is done the original open CollapsingHeader is shown again.

During debugging i could see that the dragged CollapsingHeader uses a different id then the original one in the list.

Example code of dnd with CollapsingHeader:
Icekey@20bc876