The Standard Model of Particle Physics Predicts G Factors

The standard model of particle physics predicts g factors for certain for all the particles, right? Thik, that's the whole point of the standard model. However, a with a recent experiment a couple of years back, they did it on the muon, and they found that the experimental results were about three sigma away from the standard model predictions. So this is literally almost calling for a new theory or we're just not understanding something about the original one.