Flux variation gradient applied to set of light curves from our LSST mock catalog. Left panel: light curves with an average time sampling of Δt = 3 days, S/N = 30, and total time span of T = 200 days. Low and high levels of AGN activity are marked with blue and magenta circles, respectively. Right panel: FVG analysis for the u and g bands only. Other bands are given in Fig. A.2. The dotted orange and black lines cover the upper and lower standard deviations of the OLS bisector fit (solid lines) for the combined (black) and higher (orange) AGN state of activity. The color of the Sa galaxy we used in the simulations is shown as a dotted red line.