Synthetic transmission spectra derived from our 3D simulation for the density I (red solid line) and density II (blue solid line) setups. As for the underlying observations (gray), a time average between the optical second and third transit contact is displayed. The shaded regions represent the range of model transmission spectra obtained during the transit. The synthetic spectra are multiplied by a factor of 1.00191 (Sect. 3.4.4) to match the observational continuum. The red solid line aligns well with the observed helium triplet, while the location of the secondary red component can be reproduced by considering a higher density of the same outflow structure.