What is this 10GB "Apple Music" folder within my Music folder?

Hi! My Mac is running out of storage. The largest item is my Music library. I've maintained it since before having a subscription to any music service, and I keep my library offline. I do use AM for new music, and I have a few playlists on it, but I don't have them downloaded to my Mac, I only do that for music that I own and is in my library.

So I was surprised when I opened the ~/Music folder. Within it, there's a "Media" folder, of course. Within THAT, there's a "Music" folder, with all of the music from my library, but also an "Apple Music" folder with a bunch of… I don't know? Other music? It's taking up 10GB, and I think it's music I've listened to at some point, but I have no idea why it's here. How did it get here? How can I stop this from happening again? Can I safely delete it from Finder, or do I need to somehow do it through the Music app to not mess anything up?