[0.16.6.1] Seams in wood bookcase?

While building in my condo, I placed down a wood bookshelf item and it has 2 very thin seams you can see through (Pictured below) Is this normal?

Steps to Reproduce

Place down a wood bookshelf and see if you can see through it.

What I expected to happen

To not be able to see the white plaster wall behind the bookshelf

What happened

I saw the plaster wall behind the bookshelf lol


Notes / Media