Currently a item used in Creative reduce the count to 0 and 1 later, in this process CB apply an additional restore of count and components (NMS ItemStack) for what the item lose the Components.

This can be replicated with the follow.

/give @s minecraft:cat_spawn_egg[minecraft:max_stack_size=1,minecraft:max_damage=100,minecraft:damage=10] 1 

This command give a item with custom components, being used in creative make this components lose