BgVri, ZTF gri, and ATLAS c, o-band light curves of SN 2021tsz offset by values as shown in the legend. ZTF gri magnitudes are in the SDSS photometric system. The absolute magnitudes are corrected for distance and reddening as listed in Table A.1. Parametrised fit to the r and i band light curves are also shown (Olivares et al. 2010). The vertical grey lines denote the epochs at which a spectrum of SN 2021tsz was obtained.