Why does my smartObject in photoshop have content outside its Canvas?

When I pull in my .PSB into a new .PSD, for some reason it brings in content that sits outside the Width / Height of the Canvas.

I know I can go about creating a mask or cropping it out in the original .PSB, but is there a quicker way.

I'm prototyping a background image size, and want it to be easy to go back and change it without having to do all these extra steps

What am i missing? or tip i don't know? thanks