This is not to say you are wrong, maybe I have mis interpreted what I have seen.

However I have seen it.... and I have also seen things like "blue" 2D 'flat' squares at this location (no idea what that is yet),
plus i have seen  items belonging to user id 0 with co-ords at 0,0,0 being generated related to FP code., then moved or loaded with configs or attached.

You yourself said that the cargo ship is accountable for several of these items, and the cargo ship is FP code.
 let's not even get started about the animal noises and other sounds... and the chairs... (all of which have user ID 0)

That is not to say plugins are not responsable for many of the other issues or this particular issue(which i think it is),

Plus I have seen  different sets of items on different clients synced to the same server over a sub 1ms 20Gbs optical network, client & servers are less than 5M apart.
if it is ALL server driven that should not happen.

I found  I can get significant improvements in speed, when I take into account what i'm seeing and program for it.

But far to many of us are seeing strage things and having strange situations, for something  "Not" to be going on.

WhiteThunder

Did you get a response from FP about this? The details you provided seem incorrect. I have read the source code of the game extensively, mostly the server, but some of the client as well, and I have seen no evidence of any of your points.

Bobby0001, if you can give me access to a test server where you are experiencing this issue, I can help you debug it. I will have to develop and iterate on a plugin to get sufficient diagnostic info to determine the root cause.

Hi, could you reach out to me on Discord at [removed] and I'll get you access? Thanks I really appreciate it.

Found the culprit on Bobby0001's server: Loadoutless. Whenever a player spawned with a loadout that had attachments inside a weapon, it would double create each attachment, leaking half of them.

Caused by the following line of code.

item.contents.AddItem(BuildItem(mod, 1, 0).info, 1);

BuildItem creates an item, and AddItem also does. The one created by BuildItem was essentially discarded, only used to determine the item definition.

This issue has existed for 3 years, since v1.2.0, but Loadoutless was in a semi-broken state until it was taken over in the past year.

congrats

Thank you so much, this has been plaguing my server for weeks!