The MCMC bulk flow amplitude constraints for z <  0.07, z <  0.10, and z <  0.13 shown for the L_X − T, Y_SZ − T, and M_gas − T relations. The right panel includes injected scatter and the left panel does not. Black dashes represent the results from individual lightcones, while the thick coloured bars indicate the 16th to 84th percentile range across the lightcones. For comparison, the M21 results for L_X − T and Y_SZ − T are shown with their original error bars, corresponding to redshift spheres of z <  0.06, z <  0.07, z <  0.10, and z <  0.16. To avoid visual overlap, the points for L_X − T and M_gas − T are slightly offset along the x-axis. The black dashed line represents the median true average bulk motion of the clusters, with the grey shaded region indicating the 16th to 84th percentile range of the lightcones. (a) No scatter. (b) Matched scatter.