Ratios between σ_tot (Eq. 6) and σ_int (Eq. 7) as a function of input magnitude. The measured shape noise σ_tot includes corrections for both multiplicative and additive biases, while the intrinsic shape noise σ_int is corrected for detection bias (see text for details). For the Euclid-like survey, the ratios remain consistent between the grid-based and randomly placed galaxy configurations. In contrast, the increasing discrepancy between the LSST-like setups highlights the growing impact of blending at fainter magnitudes.