Intrinsic CCFs occulted by TOI-421 b. Top: flux map, as a function of RV in the star rest frame (in abscissa) and orbital phase (in ordinate). The core of the stellar line is barely visible in individual exposures, but detectable through the joint RMR fit. The green solid line shows the best-fit surface RV model. Transit contacts are shown as green dashed lines. Middle: weighted average of intrinsic CCFs aligned in a common rest frame, with a Gaussian fit to highlight the line shape. Bottom: residuals between the disk-integrated master-out and individual CCFs (outside of transit) and between intrinsic CCFs and their best-fit RMR model (during transit).