Temporal evolution of the He I signal. Top panel: color scheme for the CARMENES spectra: pre-transit (black), ingress (blue), start (magenta), center (red), end (orange), egress (green), and post-transit (cyan). Horizontal bars represent the 5 min duration of the exposures. The transit model for HD 235088 b from Juliet (black solid line) is superimposed. Bottom panel: transmission spectra (TS) around the He I triplet line for the transit phases from top to bottom (consecutively offset by 2%). We show each TS binned by 0.2 Å with its uncertainties. Dashed black horizontal lines indicate the 0% level in each case, and dotted grey vertical line indicate the He I triplet line position. The wavelengths in this figure are given in vacuum.