0. ALWAYS PROVIDE INFORMATION ABOUT MODLOADER (Fabric / Forge) AND MOD VERSION (For Example 1.19.2-8.2.10)
   Fabric 1.20.1-9.1.9

1. Describe the bug
   When using the button to take the backpack off, I have had the backpack vanish twice rather than receiving it as an item, in both cases I had available inventory space.

2. Write steps to reproduce the bug
   I don't know how to reliably reproduce the bug, I take the backpack off to place/use the sleeping bag often, but twice I have tried to take it off and ended up losing the backpack.

This happens on a server I own and run. 99% of the time everything works normally, but so far I have had my backpack vanish twice rather than receiving it as an item when taking it off. I have verified that there are no errors in the server console, it is not a client only issue, and reconnecting/restarting the server has no effect. I have no clue how to reproduce it and don't see anything in common between the two times it happened, but it's making me paranoid about losing it and all the items contained, to the point where I'm going to have to make a creative copy of it and store it in a random player's ender chest as a backup.

Edit: I just realized that with this most recent deletion, I lost several AE2 spatial storage cells that can't be replaced. This is incredibly frustrating and is something that even with full admin access, I simply can't fix.

I haven't encountered this bug, without reproduction steps there's not much I can do, it might be compatibility issue or something

@Tiviacz1337 Good and bad news. The bad news is I still don't know how to reproduce it or why, but the good news is that it turned out that in both cases the backpack was picked up by my magnet card and ended up in my ME system.

This means it's not actually an item deletion bug, just more of quirky behavior where rather than the item being placed in my inventory, it presumably exists for a brief moment as an item entity.

I'll close this issue for now as being invalid/mostly user error. It's up to you if you care/want to look into why/how the backpack would exist as an item, or if it even matters. Thanks, have a good one!