Pseudo-bolometric lightcurve of SN 2020bqj based on trapezoidal integration of the broadband fluxes. Overplotted are TIGERFIT model fits (see Sect. 6). The radioactive ⁵⁶Ni decay model fit has t₀ set to −2 days before our adopted estimated explosion epoch. The hybrid CSM+Ni model fits shown assume a CSM shell (s = 0) or a wind profile (s = 2), with t₀ set to −4 and −3 days, respectively. The radioactive decay model does not reproduce the transitions between the rapid rise, plateau and decline phases. The hybrid models recover the shape of the lightcurve much better, in particular the Ni+CSM shell (s = 0) model shows similar sharp transitions as the data. None of the models recover the rapid rise from the latest non-detection to discovery 2.8 rest-frame days later. Phase is relative to estimated explosion epoch.