Secular evolution of the epoch-averaged FWHM of Stokes I. The scale on the left refers to optical data, while on the right to the near-infrared, and the colours indicate the use of different masks similar to Fig. 3. Both optical (circles) and near-infrared (pluses) observations feature a long-term variation, which is enhanced (quenched) when using magnetically sensitive (insensitive) lines. We note that the optical data point of 2019 falls behind the near-infrared ones when using magnetically sensitive lines.