Black hole masses versus bolometric luminosities. We show quasars at 0.35 < z < 2.25 from the SDSS DR7 survey (black contours and grey points), and a sample of z > 5.8 quasars from the literature (blue points, see Sect. 4.3 for references). We report the newly calculated values for the core XQR-30 quasars in red diamonds, and the additional 12 high-z sources in golden diamonds. Typical systematic uncertainty on black hole masses, due to the scaling relations used (∼0.55 dex), is shown in the bottom right corner. Distributions of bolometric luminosities, black hole masses, and Eddington ratios for all the above described samples are also reported.