Spoofing attacks pose a threat to drones that can lead to their crash or takeover. As a countermeasure, the European Space Agency has implemented the Timed Efficient Loss-tolerant Authentication (TESLA) broadcast protocol in the Galileo Open Service Navigation Message Authentication (OSNMA) to detect such events. This study explores the application of TESLA in detecting spoofing attacks targeted at drone swarms that rely on positioning systems utilizing ultra-wideband (UWB) technology. The results of our experiments reaffirm that UWB-based positioning systems are not automatically invulnerable from spoofing attacks and that cryptographic methods such as TESLA are required to provide a layer of protection against spoofing attacks to detect them effectively.