Stars & Wishes is a tool designed within the Gauntlet RPG community, which I've found super useful. The creators can speak on it much more effectively (and authoritatively!) than me, so here's a cool thread about it: https://www.gauntlet-rpg.com/blog/stars-and-wishes
At my own tables, we use the basic version. There's no mechanical effect to Stars & Wishes, it's just a nice way to end on a positive note and generate constructive criticism in a kind and supportive way.