This is something I don’t usually do, but wanted to share some thoughts.
Here’s a little detail from Chapter 903: Kobe was adorned as a naval hero during the “Rocky Harbor Incident” to protect citizens.
So I wonder if Law and Coby ever fought, or if they teamed up to take down other pirates, or what happened. Of course, Oda has brought us some interesting and mysterious things again!
Then I remembered how Luo became Shichibukai by sending the hearts of 100 pirates to the Admiralty, when explained in the animation, this seems to be directly related to the Rocky Harbor incident, so the two cases are likely the same incident a part of.
All in all, my guess is that Luo orchestrated the events of Rocky Harbor by (mistakenly) leading a relatively large number of pirates to raid coastal villages.
Coincidentally, Kobe was also in town protecting the citizens.
The battle between the pirates and the navy was in full swing, Luo turned around, “exploited” their hearts one by one, stopped the attack, and became a warlord.
You could argue that Luo is not the type to betray his allies, and while I agree that he wouldn’t betray Luffy, the same point was clearly made when the Straw Hats first discussed alliances with him, so it was a A great way to refer to this particular “event”.
I’ve also considered some other guesses, but I’ll leave them out for now.