The Compton y-distortion quantifies the deviation of the Cosmic Microwave Background (CMB) spectrum from a perfect blackbody, primarily caused by the inverse Compton scattering of CMB photons by hot electrons (the thermal Sunyaev-Zel'dovich effect). A persistent tension exists where the amplitude of the y-distortion signal measured by Planck implies a lower density of matter fluctuations (sigma_8) or less thermal energy in the intracluster medium than predicted by the standard Lambda-CDM model fitted to primary CMB anisotropies, suggesting either missing feedback physics or suppressed structure growth (Hill et al. 2014; Planck Collaboration 2016).