NIRSpec fixed slit (λ < 31 160 Å) and extracted 1D spectrum from the Band III data (λ > 31 160 Å) of VDES J0020–3653. The modulation of the flux, which is particularly pronounced around ∼18 000 and ∼30 000 Å here and also the other quasar spectra, is caused by the coarse sampling of the spectrum described in Sect. 2. The associated error spectrum is shown in grey. With the very high S/N ratio of the spectrum, the error spectrum appears virtually at the zero-flux level.