SM21 preferred model prediction and contemporaneous observed data. The HIRES data have been scaled and offset by linear parameters that minimize the residual spread with respect to the GP model, and the median 4p_PQP2 CARMENES data RV zero-point value was been applied in order to compare both data sets more easily with the model expectations. Top: mean model prediction (gray solid line), together with contemporaneous HARPS-N (black), CARMENES (red), and HIRES (purple) RVs overplotted. Bottom: model residuals, together with 1 and 2σ GP uncertainty bands (shaded dark and light gray regions, respectively). Takeaway: the preferred SM21 model is overfitting the HARPS-N data, which can be seen in the increased spread about the residual = 0 line for both HIRES and CARMENES data during epochs with contemporaneous HARPS-N data.