DESI and SDSS spectra of J0845+2127 for three epochs. The continuum fluxes for the 2018 and 2021 epochs are matched to that of the 2012 SDSS spectra to highlight variability in the absorption features. The top panel shows the strengthening of C IV BAL with v ∼ −22 000 km s⁻¹ over time. The bottom panel shows the emergence of a C IV BAL with v ∼ −39 000 km s⁻¹ between 4820 and 4890 Å. The apparent increase in the depth of the narrow intervening features in both panels is a result of the higher resolution of the DESI spectrum.