Recently, the ANITA collaboration announced the detection of new, unsettling Ultra-High-Energy (UHE) events. Understanding their origin is pressing to ensure success of the incoming UHE neutrino program. In this talk, I will discuss the ANITA-IV events in contrast with the lack of observations in the IceCube Neutrino Observatory. I will introduce a general framework to study the compatibility between these two observatories both in the SM and Beyond Standard Model (BSM) scenarios. In this framework, I will discuss the constraints on BSM and highlight the importance of simultaneous observations by high-energy optical neutrino telescopes and new, UHE detectors to uncover cosmogenic neutrinos or discover new physics. Finally, I will briefly discuss possible BSM extensions that could fit into these experimental constraints and their astrophysical implications.