Sunken Airdrops

[Tapioca]

I paused the game to go and eat some food but when I came back and hit continue, the game suddenly spammed me with "Sunken Airdrop Complete". Not thinking too much of it, I just Quit, then Continued the game thinking it was just bugging out.

After a couple hours of gameplay, I noticed that my map already marked a couple of airdrops and had check marks on them even though I haven't been to the place. I tried going there but all of them seem to have already been opened. Is it possible for other players to Join your game and take your loot? Or is it just a bug? If it's possible for other players to do that, I'd be happy to just play the game offline to be honest since this is my first playthrough and I was also interested what those Airdrops had in them :/