The EDGES experiment reported a deep absorption trough in the global 21-cm radio spectrum centered at 78 MHz (z ~ 17), with an amplitude of -500 mK. This signal is roughly twice as deep as the maximum absorption predicted by standard Lambda-CDM models (-230 mK), which assume adiabatic cooling of the gas. Explaining such a deep trough requires either the primordial gas to be significantly colder than expected (possibly interacting with cold dark matter) or the radio background at Cosmic Dawn to be significantly brighter than the CMB (possibly from early black holes or decaying particles). However, the SARAS 3 experiment subsequently failed to verify this signal, creating a tension between experimental results and standard theoretical expectations (Bowman et al. 2018; Singh et al. 2022).