SFR (σ_SFR, upper panel) and gas metallicity (σ_Z, lower panel) rms variations as a function of stellar mass for the sets of models presented in Fig. 4 (see Eqs. (3) for the definitions). As a reference, we report the SERRA average σ_SFR (Pallottini & Ferrara 2023) and σ_Z (this work), the σ_SFR from Ciesla et al. (2024), Mason et al. (2023), Muñoz et al. (2023), Shen et al. (2023), and the σ_Z for FIRE-2 at z = 8.0 (Marszewski et al. 2024) and JWST data. Note that ⟨JWST⟩ is the rms of the observations after subtraction of the fit to the MZR in the different datasets in Nakajima et al. (2023) and Curti et al. (2024); the thickness of the shaded area encloses the minimum and maximum of the rms of the different datasets.