Total magnitude light curves of SDSS1335+0728 in the ZTF g (green), r (red), and i (yellow) bands, CRTS (blue), WISE W1 (gold), and W2 (light green) bands, and in the ASAS-SN V (pink) and g (brown) bands. The black circles show the binned light curves constructed using bins of 180 days. The black dashed line marks the day when ZTF19acnskyy started triggering alerts in the ZTF alert stream. The red dashed lines mark the dates with available spectra, and the grey dashed-dotted lines show the dates with available Swift/UVOT observations (more details on Sect. 3).