Same situation as in #138793, so same solution as 1cb20d444e
Converting from text (via legacy curves) to grease pencil with "Keep
Original" option enabled can cause the new grease pencil ID to not be
evaluated, leading to an situation where a evaluated grease pencil
object would point to the original legacy curve ID as its object data.
This fix added a depsgraph tag so it ensures the COW ID is the latest.
Pull Request: https://projects.blender.org/blender/blender/pulls/146314