I have checked countless times to make sure this wasn’t my Internet, but I have found a way to get as many arrows as you want for no cost whatsoever.
To replicate the bug, what you must do is type in /is to bring up the Island Menu. Go to Leaderboards, and then click on Next Page. I haven’t actually gotten that specific function to work, and instead I can take the arrow that represents the option out of the pseudo-inventory and into my own inventory.
Granted, getting a full stack is quite time-consuming and boring, but it’s definitely faster and much cheaper for poor players to simply do this rather than get the materials to craft arrows in bulk.
I hope you can get on this issue fast. We don’t need PvP to already be broken.