I do the same thing, although I typically put on something lightweight that I’ve seen before, like a season of Parks & Rec. It’s interesting to see someone else with this specific experience, I always used the analogy of “picking up the slack”.

If I am engaging in rote work that doesn’t require much creativity or doesn’t fully engage my mind, then part of my attention tends to wander. It might not lead to total distraction, but it does produce an uneasy feeling I describe as anxiety.

I always imagined that music can serve a similar function in others, but I believe that my having been a musician (and a serious one when I was younger) causes me to engage a little too deeply into whatever music is playing, so it’s a little too active for me.