Period-radius diagram of the M-dwarf population of sub-Neptunes, using the same sample as in Fig. 8. Planets are colour-coded according to their density, as in Fig. 9. The green-dashed and purple-dotted lines mark the position of the radius gap for M dwarfs estimated by Van Eylen et al. (2021) and Venturini et al. (2024), respectively. The two planets under analysis are highlighted with diamonds. The blue lines on the histogram, which shows the radius distribution of the sample, marks the radius values of the two targets.