In absolutely no fairness to Jujutsu Kaisen Rowling, she probably hadn't come up with the enslaved house elves in the first book, they only come up in the second and then are retroactively explained to be responsible for the kitchen (and maybe some other tasks?) at the school. So she's a hack definitely she had no plan when writing any of the first four-or-so books but retconned and added so many world building elements and plot points as she continued to write.

I think the podcast I remember hearing this first on was the Shrieking Shack podcast or something I think it was called? I'll try to remember the name

Ayup. Shrieking Shack podcast