Posterior TTVs of TOI-1227 b computed relative to a linear ephemeris (from the MAP value of the sinusoidal model) are shown with black error bars (Sect. 3). In the upper panel, the TTVs’ sinusoidal model (median, 1, 2, and 3σ, in gray) is shown and compared with individual transit-time determinations (Sect. 3, median and 68% CI, the colors of the dots indicate the observing band as in Fig. 1). The linear ephemeris from Mann et al. (2022) is shown as a red line. In the lower panel, the posterior median of the TTVs’ model was subtracted to visualize the uncertainty of the distribution and to allow for better comparison with the individual transit-time determinations.