Gamma-ray spectra computed within the conventional (Base) and γ-optimized scenarios compared to Tibet ASγ (Amenomori et al. 2021) and LHAASO (Zhao et al. 2021; preliminary) data in the window |b|< 5°, 25° < l <  100°. The Galactic diffusion emission spectrum measured by Fermi-LAT and extracted as discussed in Sect. 2.2, and the ARGO-YBJ data (Bartoli et al. 2015) in the same region, are also shown. The contribution of unresolved sources, which may be significant at the highest energies, is not shown. The models account for the effect of γ-ray absorption onto the CMB photons (see Sect. 3.2).