Luminosity-to-mass ratio unveiled by PPMAP. Top panel: we show the complete histogram of L/M across the 15 ALMA-IMF regions studied, separated into two samples by the equation log(L/M) = 1.8. Bottom panel: as an example, a decomposition of the evolved G012.80 protocluster’s luminosity map is performed. Pixels with higher luminosity-to-mass ratio (log(L/M) ≥ 1.8 are plotted with a red col-ormap, while their counterpart (log(L/M) ≤ 1.8) are shown with a blue colormap. Superimposed white contours illustrate the H41α line emission, that traces regions dominated by free-free emission (contour levels: logarithmically spaced between 0.025 and 0.075 Jy beam⁻¹). Green contours illustrate the NeII line emission (contour levels: logarithmically spaced between 0.005 and 0.04 erg s⁻¹ cm⁻² sr⁻¹).