Phase-folded transit light curve of WASP-189 b after correction of instrumental systematics and stellar activity. The top panel shows the normalised flux and two best-fit transit models with and without GD. The mid-panel (blue-point residuals) shows the best-fit residuals for the model accounting for GD. The bottom panel displays the residuals after removing a transit light curve without accounting for the gravity-darkened stellar photosphere. The black dashed line is the deviation of the model without GD from the model with GD.