Surfaces not looking right form imported OBJ

I’m sure this is a very easy fix but I don’t know why surfaces are looking like this…

I import the obj and then I sharp shade it comes out with this result. I’m still quite new to materials but I’m not 100% sure what is happening here and I would love to be able to understand why.

Here is my blender file : Potion.blend (587.5 KB)

Can’t check the file right now, but try deleting any custom split normals.

You are my Legend…

Thank you!