Fiducial COSMOS photometry-derived stellar mass, colour excess, and age distributions of the stable intermediate-z galaxies (in light brown) and the z > 6 contaminants. The latter are divided into three samples: contaminants with fiducial z = 1–3.5 (in hatched green), contaminants with fiducial z = 3.5–5 (in red) and contaminants with fiducial z = 5–6 (in purple). The median of each distribution is indicated with a vertical line in a corresponding colour. The upper panels show contaminants identified from Euclid data alone, and the lower panels show contaminants identified from Euclid+H20+Spitzer data.