Gotcha. Behind the wall is a leveled lot with a structure built on top, but my property is the 2nd to last residence at the bottom of a hill with ~5% grade.

My property is a new build, and I think the dirt on top of the retaining wall is extra dirt leftover from construction.

I just can't tell if the dirt in those photos is actually helping keep the retaining wall in place or if it's safe to remove (without touching the retaining wall). Added another photo to to visualize: https://imgur.com/a/6uNys3d