Γ vs. v_C․IV for our sample of z > 6 QSOs (red stars) compared with a sample of luminous QSOs at z < 6: the WISSH QSOs at z = 2 − 4 (Zappacosta et al. 2020) (green diamonds) and blue QSO at z ≃ 3.0 − 3.3 (Nardini et al. 2019; Lusso et al. 2021) (blue inverted triangles). We report the linear relations we found for our sample of QSOs at z > 6 (red dot-dashed line) and for the combined sample of lower z QSOs (black dashed line). The shaded regions represent the combined 1σ error on the slope and normalization.