Custom item with minecraft:max_stack_size = 1 still allows stacking to 64

Steps to Reproduce:
1. If I use Format 1.20 for a custom item, then I use the "minecraft:max_stack_size" component, it will always set to 64 even if I set the value to 1
(See the second picture)

Observed Results:
It's not working, and it stacks to 64 (See the First picture)

Expected Results:
can only be stacked by 1 item per slot.