Galaxy counts and distance–redshift surveys suggest that the region around the Local Group out to a few hundred megaparsecs may be significantly underdense in matter (the so-called KBC “local void” or Local Hole), with estimates of a 20–50% deficit compared to the cosmic mean (Keenan et al. 2013; Haslbauer et al. 2020). If such a large, deep underdensity is real, it challenges ΛCDM both statistically—voids of that scale and depth are rare in simulations—and dynamically, because while it can raise the locally inferred H0, detailed analyses indicate that a ΛCDM void cannot fully account for the observed Hubble tension without conflicting with BAO, supernova, and large-scale structure constraints (Huterer & Wu 2023; Stiskalek et al. 2025).