There are widespread assumptions to the effect that the real-time data generated through the 5G-enabled Internet of Things (IoT) will improve material traceability and accelerate the global transition to a circular economy (CE), thereby helping to achieve the UN Sustainable Development Goals and carbon neutrality. Many industries, governments, and NGOs are supporting this vision by investing in related digital infrastructure (5G networks, servers, computer hardware, etc.). Conversely, recent literature has highlighted a paradoxical phenomenon known as the CE rebound, whereby sound CE activities end up offsetting environmental gain(s). This challenges the assumption that the new 5G-enabled IoT will be conducive to greater circularity while carrying its own environmental weight. Resorting to applied epistemology—a perspective seldom used in sustainability research—and the global e-waste crisis as an intense case in point, we question the confidence with which actors predict positive outcomes from the CE–IoT nexus. We argue that avoiding circularity rebounds cannot be construed as a matter of methodological development or, by extension, modeling sophistication through real-time data exploitation. Instead, circularity rebounds need to be recognized and theorized as a paradox of knowledge that also narrows sustainability research’s horizons, despite AND because of the 5G-enabled IoT. As per this paradox, advanced digital technologies may well be compounding environmental issues at the same time as they illuminate them.