pEWs of the He I IR line as a function of the pEWs of the He I D₃ (left panel), and Hα (right panel) lines. Black crosses represent the nonflaring models from Hintz et al. (2019). Series A and B are depicted by color-coded squares (the color-coding corresponds to that of Fig. 2). CARMENES observations of the investigated M 2–M 3 V stars are flagged by red pluses. In the observed pEW(He I D₃) of the stellar sample, we add an offset of 0.06 Å because these measurements are influenced by a decline in flux in the respective normalization reference bands from the blue to the red continuum.