Question Timeline "Prefab asset found assigned to an output of type Animation" warning

I created a timeline in a Prefab. And all the game objects I use in the timeline are in that prefab.

"Prefab asset found assigned to an output of type Animation, which will have no effect. Assign an instance of the prefab instead."

However, when I play this timeline in another scene, I always get this warning. I couldn't make any sense out of it. Does the warning mention that it won't be saved as long as the Timeline is in a Prefab?