[CII] outflows parameters. (a): Mass outflow rate as a function of L_AGN for the different stacked spectra (stars, see legend for details), compared to the sample of 30 low-redshift AGN from Fluetsch et al. (2019) for which spatially resolved molecular (blue) and, in one third of the sample, ionised (green) outflows have been observed. We also included the compilation of ionised outflows (hollow green squares) with spatial information in z ∼ 0.1−3 AGN from Fiore et al. (2017), recomputed according to Eqs. (4)–(6). Purple squares are local systems for which the outflow has been traced in [CII] through observations with the Herschel Space Observatory (Janssen et al. 2016; Fluetsch et al. 2019). By applying the atomic-to-molecular outflowing gas mass correction by Fluetsch et al. (2019), the molecular+atomic mass outflow rates are shown with circles. The typical ∼0.3 dex uncertainty on Ṁ_out for the [CII] outflows found in our z ∼ 6 QSOs (similar to that of outflows in the atomic neutral and molecular phase in low-z AGN) is shown by the black solid line, while the uncertainty on Ṁ_out for the ionised outflows is shown by the green line. (b): Outflow velocity as a function of L_AGN. (c): Kinetic power as a function of L_AGN. The dotted, dashed, solid and dot-dashed curves indicate kinetic powers that are 10%, 1%, 0.1% and 0.01% of the AGN luminosity. (d): Momentum load factor as a function of the outflow velocity. The horizontal line corresponds to Ṗ_out = P_AGN.