Solid lines: the energy flux of secondary leptons produced by pγ interactions in a 3 Mpc magnetised region around a source at redshift z = 0.14 that emits UHECRs with L_cr,iso = 10⁴⁷ erg s^-1. The volume-averaged magnetic field strength in the magnetised region is . The noise in the pion bump is due to the finite number of particles injected in our simulations. Dot-dashed lines: the energy flux of secondary leptons produced by pγ interactions beyond the first 3 Mpc of propagation.