Investigating the effects of different uncertainties: Distribution of ⟨V_R⟩ in the (x − y)-plane for the Gaia-like mock dataset at t = 3 Gyr, showcasing how the observed quadrupole feature is affected by errors in proper motion, radial velocity (V_R), and parallax. Top-left panel: stars in the snapshot (no uncertainties and no magnitude cut). Top-middle panel: magnitude-limited G ≤ 15.5 mock dataset with no errors. The top-right and the bottom-left panels show the mock datasets with only proper motion (PM) uncertainty and both the PM and radial velocity uncertainties, respectively. The bottom-middle panel shows the mock dataset resampled according to the errors in the Gaia DR3 RGB subsample (see Section 4.2). The bottom-right panel shows the mock dataset where all the particles have had their V_R set to zero prior to applying observational effects. For further details, see Sect. 4.3.