Evolution of the orbital distance of pebbles as they drift through a disc with an embedded 25 M_E planet, where the radial velocity is fixed to − 1 × 10⁻⁵c_s,0 (top) and − 3 × 10⁻⁵c_s,0 (bottom). As the drift speed of the particles depends on the gas velocities, particles of different sizes cannot be blocked or drift through compared to the nominal case shown in Fig. 8. In particular, a slower gas flow allows for a more efficient particle trapping in the pressure bump generated by the planet.