It's currently from Christmas Chronicles even though it doesn't come with the install. Is there a way to change it? It reads in this ModDB change log that there's custom ones but I don't see any options to change it. https://www.moddb.com/mods/jazz-jackrabbit-2-plus/news/jazz-jackrabbit-2-plus-v56-release

JJ2+ overrides standard menu theming with Christmas Chronicles theming during the winter months, i.e. December through February. If you want to get rid of it early, see https://www.jazz2online.com/jcf/showpost.php?p=495123&postcount=1601