Joining with armour equipped will move all armour up into the wrong slot

[slushie0]

Description

When I join my world, I have 4 armour slots (head, chest, legs, feet) or 1, 2, 3, and 4 respectively. When I join, I had nothing in slot 1, elytra in slot 2, leggings in slot 3, and boots in slot 4. And I'm not sure if this happened on my first join or second join, but all my armour was shifted up 1 slot so there was no more space above any armour, and slot 4 was empty. I had elytra in slot 1, leggings in slot 2, and boots in slot 3. I can't test different combinations because if I try to remove armour from a slot, it just gets put back after I rejoin. However when I move the armour back the the correct spot, it won't let me place it back in the wrong spot. The console looks completely normal.

Steps to reproduce

1. Start the server
2. Make sure you have armour equipped, with at least 1 empty slot
3. Rejoin
4. The armour will be in the wrong spots

Expected behaviour

I would expect the armour to be in the correct place when I rejoin

Details

• Server version: Krypton 0.64-355
• Java version: OpenJDK 18.0.1 JRE