The relationship between the stellar mass of galaxies and the mass of their surrounding dark matter halos shows systematic tensions and unexpected features that Lambda-CDM struggles to explain, particularly at both the low-mass and high-mass ends of the galaxy distribution. Observations reveal that the stellar-to-halo mass ratio peaks at intermediate halo masses and declines steeply toward both smaller and larger halos, with the efficiency of converting baryons into stars being surprisingly low overall—only about 10-20 percent of available baryons end up in stars even in the most efficient halos (Behroozi 2013; Moster 2018). Lambda-CDM has difficulty explaining why this relation has its observed shape, why star formation efficiency varies so dramatically with halo mass, why there appears to be a characteristic mass scale where efficiency peaks, and why high-redshift observations with JWST show galaxies that appear to have stellar masses inconsistent with their expected halo masses based on the standard relation, suggesting either the relation evolves differently than predicted or that massive galaxies formed their stars much more efficiently in the early universe than current models allow.