Generalised Lomb–Scargle periodogram of the HARPS RVs and stellar activity indicators. The horizontal lines mark the bootstrap false alarm probabilities at 0.1 and 1.0% as indicated in the legend. The orbital frequency of TOI-2196 b (v_b = 0.837 day⁻¹) is marked with a vertical thick yellow line, while the corresponding period is reported in the upper x-axis (P_orb ≈ 1.2 day). The 1 day alias of planet b is marked with a vertical dashed red line (1 − 0.837 = 0.163 day⁻¹), a) RV measurements, b) RV residuals with the best-fitting Keplerian orbit of planet b subtracted, c) RV residuals following the subtraction of both the linear trend and the Doppler signal induced by planet b. d–h) Activity indicators and line profile variations, i) The window function.