If I remember right the houses in the soundstages sort of butt up against a shared area where the actors take breaks, get costumes, etc... so they build the houses so the guest paths avoid that sort of shared spot but that may or may not align with where the masking curtains normally hang on tracks in the stages.
Long story short, the buildings come with build in "stuff" and that can include large hanging black curtains that can be moved on a track to divide the space. Where they align with the plans - yay! - they get used there to stop light bleed and such. But where they don't you either hang some curtains on their own or you build large fabric panels to use as masking.
But you can also build a small segment of panel that the existing curtains can clip on to the side of - since this shot appears to be from an entry or exit door. So they use the curtains as they able to be hung to hide the house from entering guests and then attach it to the panel section just to anchor it and give a less obvious end of the masking than the dusty edge of an old curtain.
It's so tall because those curtains essentially go floor to ceiling.