Posterior distributions on the parameters Ω_m and σ₈ from the ΛCDM fit on eRASS1 data shown in orange. In blue, we show the Planck CMB 2020 constraints without combination with BAO and SNe Ia Planck Collaboration VI (2020). In red, we show the combination of eRASS1 with Planck CMB. As a comparison, we also present previous results from similar cluster surveys that employ weak lensing shear data in their mass calibration, e.g., WtG (Mantz et al. 2015), DES (Dark Energy Survey Collaboration 2020), SPT-SZ (Bocquet et al. 2019), eFEDS (Chiu et al. 2023), XXL (Garrel et al. 2022), and SPT (Bocquet et al. 2024) surveys.