There is probably some physics equation that explains things, but I’m not that smart. 😉
My other thought is that with a mold that deep and a pour that shallow, it’s probably very hard to get the glitter right up next to the edge. You may have to get with a shallower mold. Either that or you’re going to have to dump more glitter on, which may not give you the nice stripes you’re trying to make. We have heart molds for resin in our store here: https://shop.resinobsession.com/collections/molds/hearts