Minecraft snapshot 24w12a introduces an item stack component for hiding the tooltip, aptly named minecraft:hide_tooltip. However, when this component is assigned to an item stack, the tooltip will still be shown when initially selecting an item in the hotbar.

Since the component name refers to tooltips (and not just slot tooltips), I would expect every instance of a tooltip appearing tied specifically to a certain item stack to follow that component. We know from a removed option named heldItemTooltips that the label above the hotbar is indeed a tooltip. Therefore, I believe this to be an oversight in the component's implementation.

Steps to reproduce

1. Obtain an item with the hide tooltip component: /give @s minecraft:diamond_block[minecraft:hide_tooltip=\{\}]
2. Switch back and forth between this item in the hotbar.
3. Observe that the name 'Diamond Block' appears.

Note: a workaround does exist in /give @s minecraft:diamond_block[minecraft:custom_name='\{"text":""\}'], but this workaround affects the item name in other places as well, so it is not a true workaround.