Stephanie, in this episode, is wearing a cast on her left arm. She broke her arm while shooting the previous episode, and the producers decided to cover it up. You can see that in the said episode, Stephanie doesn't move her arm much, especially in the scene where they all see the lottery with Joey. They decided to add the incident to the story in this episode, so they wrote the pizza gig to explain to the cast. Interestingly enough, Jodie Sweetin injured her ankle before season 3 of Fuller House, and her injury is written into an episode of that show as well.