NOT/ALFOSC spectra of Galaxies A (black) and B (blue) and the GTC/OSIRIS spectrum of SN 2023aew at +131 d showing narrow host lines (purple). Savitzky–Golay smoothing has been applied to the original ALFOSC spectra (gray). Identified lines of [OII], [OIII], and H at z = 0.30 are plotted as black dashed vertical lines. The same lines are also plotted at the redshift of SN 2023aew, z = 0.025, as red dotted vertical lines. No lines are detected at this redshift in Galaxies A and B.