You’ve nailed it @RichardR, that’s exactly what happens.
Our current way to “learn” about your categories is still a bit naive so this kind of exceptions happen. I’m sure we’ll improve it in the future so we learn about your actual patterns. Plus the usual sci-fi that I always like to dream about… something that could imagine that a £3 transaction at 12:30AM in Tesco is probably a meal deal and not groceries 