Unauthorized use of intellectual property. Your mom probably bought it at some Chinese import store.
Why do automatically assume its unauthorized? Licensed Mario merchandise has been around for decades. Why would a chinese importer shop be selling second hand mario merchandise from 20 years ago?
My guess is its really old and probably from the 80s or early 90s. It looks more like the Super Mario Bros. 3 era Mario than any more recent Mario, so I'm guessing this fleece came out around that time frame. So late NES or early SNES era.
ETA: Oh, I was replying to Morari. I thought you were TJ $pyke for some reason.