As someone with two daughters and who went through the teenage and young adult times with them, I believe some of you should lighten up a bit. Every age has their own music. It may not be to our taste, but it doesn't matter. It's their music, and what others may think is irrelevant, at least to them. I realize it's an old song, but Christmas tunes are different anyway. They're fair game for anyone.
On a side note, I've probably played this tune hundreds of times, but I don't recall ever doing it in E, as Ms. Eilish does.