Phenomenological constraints on the size of the neutrino source obtained by comparing the different predictions with MAGIC ULs (black points). The gray dotted curve represents the unabsorbed gamma-ray flux corresponding to the best-fit neutrino spectrum, considering only the EBL absorption, while the gray band accounts for the uncertainty in both ${\varphi }_{{\nu }_{\mu }}^{1\mathrm{TeV}}$ and Γ. Similarly, the dotted light blue and blue curves, along with their respective shaded bands, represent the gamma-ray emission with a different level of internal gamma-ray absorption, depending on the assumed source radius: 2 × 10⁴ (light blue) and 3 × 10² (blue) gravitational radii. The dark gray area below 300 GeV is not taken into account in this analysis.