Ly-α flux in Visits A (black), B (deep blue), C (light blue), D (green), E (orange), and F (red). Times are relative to the mid-transit of Kepler-444 f. All spectra have been interpolated over a common wavelength table before being integrated in the complementary wing, peak, and core bands (see text), shown from top to bottom. Fluxes have been normalized by their average over all visits (dashed line). The dotted line corresponds to the spectrum taken as reference for the out-of-transit line. Right panels show the flux distribution in each band. Cross-symbol lines delimit the 68% confidence interval around the average flux if all bands followed the same statistical variations as the wing band.