Sample of SF fitted to retrieve the slope (blue line, with an area corresponding to the 3σ level), the plateau level (orange line) and the timescales (red point, marking the intersection of the slope and the plateau). Left: SF of the April 21 Stokes I denoised light curve. Right: SF of the April 22 Stokes I light curve; we note two distinct slopes, fitted independently (the second slope corresponds to the green line).