Are noteskins licensed under MIT?

I’m assuming the default assets of the game are, but what about when you download a noteskin online from an external website?

i would call it the equivalent of uploading an image macro to twitter

And what does that mean legally?

i would say none of the user generated content is under any particular license unless otherwise stated. we arent legal experts. if you look to steal user generated content for profit that is commonly referred to as a dick move but its not up to us to tell you to stop. thats on the creators, who might not even be the ones listed as the author on the pages