Rotational modulation analysis of FWHM for EV Lac. The three upper panels correspond to the near-infrared epochs (2019b, 2020b2021a, and 2021b), whereas the three lower panels correspond to the optical epochs containing enough data points (2006, 2007, and 2010). Plotted in each panel is the phase-folded time series of FWHM computed with the full, low-g_eff, and high-g_eff mask with a horizontal line representing the mean FWHM value. For the near-infrared epochs the high-g_eff time series is colour-coded by rotational cycle to inspect signs of short-term variability. The latter can be seen as data points that are at significantly different values of FWHM at different cycles, but sharing the same rotational phase (e.g., phase 0.05 or 0.30 of the 2020b2021a epoch).