Velocity of different types of outflows as a function of L_Bol (left panel) and redshift (right panel). The green star symbol denotes the EHVO outflow of SMSS J2157 with v_out = v_max. High-redshift BALs and EHVOs from Bischetti et al. (2022) are represented as empty red circles. EHVOs from RH20 are shown as orange filled stars, while EHVOs from Vietri et al. (2022) and Bruni et al. (2019) are indicated by filled and empty magenta stars, respectively. The collection of X-ray UFOs from Fiore et al. (2017) and Matzeu et al. (2023) (SUBWAYS sample) is reported as blue and magenta triangles, respectively. In the right panel, BAL from Bischetti et al. (2023) are also shown as purple filled circles. The velocity threshold of 25 000 km/s, which distinguishes between classical low-velocity BALs and EHVOs, is shown as a red dashed line.