Upper: angular velocity ω as a function of metallicity for the whole sample of RC stars. Uncertainties on the angular velocity are derived by the fitting procedure, while the ones on the x-axis correspond to the 16th and 84th percentiles of the metallicity distribution in each bin. Lower: ages inferred from the age–metallicity relation described in Joyce et al. (2023) are assigned to the metallicity bins shown above, yielding angular velocity as a function of age. The x-axis is inverted (e.g., ages shown in reverse) for better visual alignment with the panel above.