Combined background-subtracted MOS 2 and pn light curves of CVSO 30 with a binning of 400 s. Bottom panel: soft-band light curve (0.1−1 keV). Top panel: hard-band (1−9 keV) counterpart. The adopted flare period is indicated by gray shading. Vertical lines indicate the times of fading events according to different ephemerides: the linear and quadratic ephemerides given by Yu et al. (2015) indicated by dash-dotted and dotted lines, and the ephemerides by Raetz et al. (2016) indicated by dashed lines. Two arrows indicate the potential dips discussed in Sect. 3.3.