Adobe Illustrator CC Classroom in a Book (2019 Release), First Edition

Since the drop shadow is applied to the group, it appears around the perimeter of the group, not
on each object independently. If you look in the Appearance panel right now, you’ll see the
word “Group” at the top and the Drop Shadow effect applied. The word “Contents” refers to
the content within the group. Each object in a group can have its own appearance properties.