Bundles can cause item loss if they both share the same contents, and are recombined into a larger stack.

Steps to Reproduce:

1. Give the player oversized bundles

   /give @p minecraft:bundle[minecraft:max_stack_size=99] 98
   

2. Get a stack of any item
3. Split the stack of bundles in half
   → Blocked by MC-270207, so you must hold the item in your cursor and drag the stack across two slots
4. Insert 32 of the 'other' item stack you have into each bundle
5. Combine the stacks of bundles
6. Deposit items

Observed & Expected Results:

- When the stacks are combined, up to 32 items will be deleted.
- The bundles when combined would not cause item loss.

Screenshots/Videos:

BundleItemLoss.mp4

Notes:

1. Related to MC-269789 and may be 'Won't Fix' based off it's resolution
2. This may not be possible or realistic to fix, and may not even be supported, but was reported anyways as I would consider item loss to rather important.