Comparison of spectral observations taken before and after the 2020 outburst, focusing on the Hβ and Hα emission lines. An appropriate value is subtracted to match continuum levels. Top left: close up of the Hβ wavelength range. Spectra were scaled using the average flux of the narrow [OIII] lines. Bottom left: residuals (MODS−FORS2) for Hβ. The combined uncertainties of the two spectra are shown as blue shaded bars for each spectral bin. Top right: a close up of Hα and the NII doublet. Scaling was done by comparing the average flux of the narrow [SII] lines. Bottom right: residuals and combined uncertainties for Hα.