He I transmission signals measured using observations at high spectral resolution with CARMENES, as a function of the XUV_He flux (λ < 504Å) received by the planet. The vertical axis shows the equivalent height of the He I atmosphere , normalised by its atmospheric scale height in the lower atmosphere, H, calculated assuming μ = 2.3 and the equilibrium temperature of the planets. The coloured region shows the constrained ranges defined by the He I absorption and XUV_He flux upper limits measured for WASP-76b. The information on the other exoplanets is extracted from Nortmann et al. (2018), Alonso-Floriano et al. (2019), and Palle et al. (2020a). The black arrows show upper limits on the measured He I absorption of KELT-9 b and GJ 436 b.