The longbox was the original standardized packaging format for CDs, but since the longbox itself was disposable -- the actual CD was stored in a plastic "jewel case" inside, you were supposed to keep the plastic case and throw away the longbox -- there was an outcry against them as wasteful packaging. (See for instance this article, from 1990: https://ew.com/article/1990/04/20/whats-cd-longbox/)

The recording industry loved the longbox, because it supposedly made CDs harder to shoplift. But for an industry that generally likes to consider itself progressive, being the target of protests by environmentalists was a bad look. So by the early '90s they'd given up on the longbox, dropping it completely and just shipping the CD in the plastic "jewel case" by itself.