Mean subhalo mass distribution (with equal arbitrary normalisation across the different models) computed from the 17 most massive haloes in the simulation set. The black dashed line marks the resolution limit adopted throughout the analysis (as defined in Figure 3). The three models – CDM (blue), NB (green), and FCT (orange) – show distinct behaviours. The FCT model exhibits a clear excess in the abundance of low mass subhaloes (M_vir < 10⁹ M_⊙), while at intermediate masses, the NB model overtakes the FCT model. This crossover region provides a potential discriminant between scenarios involving enhanced primordial power (NB) and those that also include PBHs (FCT). See text for further discussion.