As part of Undertale's 9th anniversary, Toby Fox has released several unfinished songs for Deltarune Chapter 2. This is one of them. Here's what he had to say about it:
"I think this is my favorite of the unfinished tracks... At least, it's the one I listened to the most when I was working on the game.
Back when Queen looked more intimidating, I wanted to use this as her boss theme. Personally I still really like it, and I even wanted to try to use it for Berdly's battle instead... but the issue was that it just didn't match either of the theme melodies I had already created for those characters.
Bizarrely, I seem to have made this after already making her theme song, as an early version of her theme song is inside of the project file.
1:30 onward (piano only) is totally unfinished."