The bug

The tooltip of an item with AttributeModifiers shows only something like "+120% Attack Damage" which is not really helpful when you don't know how much attack damage the item had at the beginning.

Expected behavior

It would probably be best if it showed always the attribute values as absolute value after applying the modifiers. This would solve the missing distinction for operation 1 and 2 (both being for example "+120% Attack Damage") as well.

How to reproduce

A good example showing that the currently displayed information is not helpful is MC-124662:
The following sword has the same attack speed like a default sword, but the tooltip says "-2.4 Attack Speed":

/give @s minecraft:diamond_sword{AttributeModifiers:[{AttributeName:"generic.attack_speed",Name:"generic.attack_speed",Amount:-2.4,Operation:0,UUID:[I;1,2,3,4],Slot:"mainhand"}]}