PNG-response (b_ϕ) as a function of the measured bias (b₁) for the tracers binned in their local overdensity. Top: Results for all haloes (purple band) together. The black dot-dashed line shows the universality relation. We find the PNG response well below the universality relation and compatible with no response (b_ϕ ∼ 0). We also show (as markers with errorbars) the results using mass bins as parent catalogues. Bottom: Same results, but for the LRGs and QSOs from PNG-UNITsim-XL.