Steps to reproduce:

1. Import and open this world
2. Press the button next to the 1st command block. This will teleport you to a water stream that goes into a nether portal
3. While in the water stream, select half a stack of diamonds in your inventory
4. Wait until you go through the portal
5. Note the Nether's nether portal coordinates (press F3 + C). Notice that the diamonds you selected have disappeared, unlike what would happen in 1.21.1
6. Press the button on the 2nd command block. This will teleport you to a stone platform where your diamonds should be
7. Compare the Nether's nether portal coordinates and the coordinates of the diamonds on the stone platform (run /data get entity @n[type=item] Pos and compare with the coordinates you copied in step 5). Notice that they are similar/same
8. Press the button next to the 3rd command block and repeat steps 2-8 except for the fact that you are travelling from the Nether to the Overworld.

Observed result:
The items you select in your inventory drop at the target dimension's nether portal's coordinates (or at least near them) in the original dimension, making them hard to find (or near impossible in certain circumstances).

Expected result:
The items you select in your inventory drop at the target dimension's nether portal's coordinates (or at least near them) in the target dimension, like in 1.21.1, making you receive the items right after entering the target dimension.

Notes:
This may also happen with end portals, however I have not tested what happens with them.