Amount of heavy elements accreted during the attached phase (including the initial core formed by pebble accretion) as a function of the initial surface density of planetesimals for different values of dust opacities (circles and squares) and considering or not envelope enrichment (triangles and circles). All the cases that reach Jupiter mass within 10 Myr of disc evolution are shown. All cases correspond to planetesimal sizes of r_p = 100 km. Red circles indicate the nominal simulations (f = 1), squared yellow points represent the case with dust opacity reduced by a factor of 10 (f = 0.1), and blue triangles indicate the case where envelope enrichment is included.