Data points show the redshift and estimated halo masses of the detected groups from our FRB 20190520B spectroscopic data. Curves show the estimated mass completeness of simulated groups and clusters as a function of redshift, assuming the observational depth and completeness of our data. The dashed curve indicates the minimum mass at which groups are detectable with N _rich ≥ 4 at the given redshift, while the solid curve indicates the mass at which we expect to be 100% complete.