When combining two enchanted unbreakable items, the result will be two stacked items

The Bug

When two enchanted & 'Unbreakable' items are combined in the grindstone GUI, the output is two stacked unenchanted items.

Steps to reproduce:

1. Run this command twice:

   /give @s netherite_sword[enchantments={levels:{'unbreaking':3}},minecraft:unbreakable={show_in_tooltip:true}]
   

2. Place down a grindstone
3. Combine the two sword items

Expected & Observed Results:

- The enchantments will be removed from the items as expected, but the unstackable items will be stacked together.
- The items would not stack, as in all other cases of gameplay they are unable to.

Videos & Screenshots:

Screenshots

Video(s)
MC-140397.mp4