What I expected to happen was...:
If you put "item_name" in the item component and hit the give command, you would have gotten a custom potion with the original name.

What actually happened was...:
But what we actually got were "Uncraftable Potions".

Steps to Reproduce:
1. Type the command "/give @p minecraft:potion[minecraft:item_name="aaaaa"]".
2. I have "Uncraftable Potions" on hand.

PS: "/give @p minecraft:potion[minecraft:custom_name='{"text": 'aaaaa', 'italic':false}'" This will solve the problem, but it is only a stopgap method.

There may be something about my English that is not very good, but that is because I am not an English speaker. Of course, I am using a translator for this English text.