The measured anticorrelation between FRB DMs and void positions at 3.2σ statistical significance. The colors correspond to three DM thresholds used to construct the nested FRB subsets for cross correlations, defined as DM ≥ DM_cut, where DM_cut ∈  {500, 750, 1000} pc cm⁻³. These subsets are sensitive to broadly different redshift ranges. We model the observed signal with an effective Universe approach (upper panel) and a uniform-density approach (lower panel). The amplitude of the measured signal is consistent with theoretical prediction from the effective Universe model (α_v = 1.80 ± 0.87) and reflects a ∼60% ± 30% underdensity of baryons in void interiors compared to the surrounding medium (δ_e,v = −0.58 ± 0.30).