Black hole masses versus bolometric luminosities. The quasars analysed in this work are reported as teal stars, compared to literature quasar samples at both higher (E-XQR-30, in yellow, and compilations from Yang et al. 2021 and Farina et al. 2022, in green) and lower (XQ-100, in purple, and WISSH, in dark red) redshift. We note that for WISSH objects black hole masses and bolometric luminosities are estimated from the Hβ line and not from the Mg II, as for all the other samples. Lastly, quasars at 0.35 < z < 2.25 from the SDSS DR7 quasar survey (Shen et al. 2011) are reported as black and grey contour lines. Typical systematic uncertainties on black hole masses (∼0.5 dex) and bolometric luminosities (∼0.3 dex) are shown in the bottom right corner.