The kinetic Sunyaev-Zeldovich (kSZ) effect occurs when cosmic microwave background photons scatter off free electrons in galaxy clusters that are moving with some bulk velocity relative to the CMB rest frame, causing a Doppler shift that appears as a temperature distortion in the CMB along that line of sight. Lambda-CDM predicts specific amplitudes and statistical properties of the kSZ signal based on the expected peculiar velocities of clusters within the cosmic web, driven by gravitational infall into overdense regions and outflow from voids. However, observational measurements have found hints that the kSZ signal is weaker than predicted—a "null hint"—suggesting either that cluster peculiar velocities are systematically lower than Lambda-CDM expects, that the electron distributions in clusters differ from models, or that some unknown effect suppresses the signal. This tension is troubling because Lambda-CDM's structure formation paradigm, with dark matter driving gravitational collapse, makes firm predictions about how fast clusters should be moving, and a systematic suppression of kSZ would indicate the velocity field of the universe differs from theoretical expectations (Hand et al. 2012; Schaan et al. 2016).