Swarm breached the "Mitigation of Orbital Debris Second Report and Order" which has been in place since 2004[0], for their launch on an Indian rocket because their 0.5Us would breach this and their aerodynamics wouldn't comply because the satellites were so small and didn't have enough atmospheric drag to bring them down in time. The tracked by radar aspect was resolvable by Leo Labs radars, but not the atmospheric drag component.

FCC subsequently fined them $900k.

[0] https://docs.fcc.gov/public/attachments/DOC-363486A1.pdf

[1] https://www.reuters.com/article/us-usa-satellite-fine-idUSKC...