Distribution of the supernova stretch parameter in the Hubble flow (left) and in the calibration galaxies (right). The stretch distribution in the Hubble flow exhibits a bimodality, which is well reproduced by a two-population Gaussian mixture model (the dashed line). The calibration supernovae are consistent with that originating from the population associated with the high-stretch peak (young population). The right panel demonstrates this property by comparing the calibration sample to the stretch distribution for type Ia supernovae found in the same comoving volume as the calibration galaxies, and to the corresponding two-population Gaussian mixture model. For the sake of better visual comparison, we keep the same normalisation of the calibration sample and the young population from the calibration volume (right panel). The Hubble constant measurement presented in this work assumes that only the young supernova population (associated with the high-stretch peak of the stretch parameter distribution) is involved in propagating Cepheid distances to the Hubble flow.