Mean difference in parallax between EDR3 and DR2. Top: parallax difference vs. magnitude. Middle and bottom: parallax difference vs. ecliptic latitude in two magnitude intervals. Circles connected by solid lines are weighted mean values computed in bins of variable size, with at least 1000 sources per bin; dashed lines are mean values of the fitted parametrised function ΔZ (Eq. (5)), binned as for the sources. Filled red circles are for ν_eff < 1.48 μm⁻¹, and open blue circles for ν_eff > 1.48 μm⁻¹.