Left and middle panels: equivalent width results for two of the Zeeman-insensitive (g_L = 0) spectral lines in our line list. Right panel: equivalent width results for the Fe ii 611.332 nm spectral line. In all panels, filled circles mark the equivalent width for the (M)HD cases, with average flux density (⟨ B_vert ⟩  = B_t = 0 =  const., i.e., equal throughout the evolution to its initial value) given in abscissas. Empty circles (here, essentially overlapping the filled ones) represent the equivalent width results obtained when artificially setting B = 0 for the spectral synthesis. The solid horizontal line marks the value of the equivalent width for the HD case. The dashed horizontal lines mark the equivalent width value obtained when decreasing the iron abundance of the HD model by 0.02,0.06, and 0.10 dex.