I'm admittedly not familiar with the theater anymore--since I separated last year, the current SPINS, etc.....
However..... if it were the US in Russia's shoes, prosecuting a war in a country with coastal lines in the Black Sea..... a water body that encapsulated critical sea lanes necessary to our supply chain, we would have declared a JOA that likely would have incorporated large portions if not all of the Black Sea. There would be NOTAMS and other types of communications circulated to the international community that the geographic confines of the JOA were apart of an armed conflict between us and whatever state we are warring with and warning third party air traffic that flight into the conflict zone would be extremely high risk and safety couldn't be guaranteed.
I'm trying to imagine this in the context of Korea, where if we kicked that off, we would likely declare most of the Yellow Sea and parts of the East China Sea as part of that JOA. And if we knew, for instance, China was operating assets in that JOA that were offering materiel wartime support to North Korea, how would we address that. Especially if we knew that support included information that directly contributed to the kill-chain cycle of the state we are warring with. TBH I don't know?
From another lens: Geneva only describes two statuses for "people" in a conflict zone. They are either combatants, or non-combatants. And either status can operate either legally, or illegally. It doesn't really outline the case of an RPA though that is not a person and is simply a materiel asset. However, with a manned aircraft, in international waters, from a non state party to the conflict, those members aboard that aircraft would be considered non-combatants. The general thing about Geneva from my understanding is that to maintain lawful status, non-combatants are expected to act as non-combatants which means not performing actions that directly involve themselves in the conflict. Providing intelligence that relates to targeting to one party of the conflict would almost definitely undermine that status and I think the case could be made at that point that you might be a combatant or an illegal non-combatant. With the former you could be lawfully targeted, with the later, you could be held criminally accountable.