There is no LEO authority over the entire world. In fact, and this may shock you, there are hardly any global authorities. Except for the sanctions and war China, for example, could decide to poison all oceans.
Actually it would be the United Nations Committee on the Peaceful Uses of Outer Space usually referred to as COPUOS. (I usually pronounce it cope-you-us because it’s slightly easier than cope-you-os for me)
Quoting a key part from its Wikipedia page …
“Resolution 1721 also further cemented the committee's role in preserving space for peaceful purposes. It stated that international law and the UN Charter applied in outer space and directed the committee to study and report on legal problems arising from space exploration. It directed all states to inform the committee of all launches into space for the UN's public registry. It directed the committee to keep close contact with governmental and non-governmental organizations concerned with space matters, as well as to act as an exchange of information relating to space activities.”
They're the authority for anything that launches from the US and that transmits on RF. If Starlink interferes with US science the FCC definitely takes that into consideration.