Scene too bright after Export

Hello!

I have a rather complex project and wanted to give a friend a simple scene so he can play around with it.
So I simplified one of my scenes (removed the scripts etc.), rightclicked on the scene and clicked on "Export package..." and included materials and textures in the package.

The import of the .unitypackage file worked, but the scene is too bright.
Here is the original scene from the original project:


And here is the second project with the scene imported via .unitypackage:


The only lighting I have in my scene is 1 directional light (selected in the screenshot) and an ambient color in the "Lighting" tab. When I disable the directional light, both scenes in the projects look the same.
When I reduce the Intensity of the Light in the imported scene to something like 0.44 the scenes look roughly the same.

Anyone knows why the scene looks so much brighter after the import via .unitypackage?

 

Guess nobody has ever encountered this problem or has an idea what could cause this?

 

I have just the same problem, no solutions?