Still curious though, 33 doesn’t seem to be a variable, it seems to be flat 33 every hit. Other items have, let’s say 1-50 lightning damage, as white and yellow text. If there is no difference between the two, why isn’t it just added together in one line?
The number in white is most helpful when looking at magical or rare items since that number represents the weapon’s base damage before modifiers. Imagine if you found a caster weapon that deals 10 base fire damage and 5 fire damage from a prefix. If the numbers weren’t separate, it would be hard for a player to tell which proportion of the damage is attributable to the weapon itself and which is the prefix.
As someone else said, the magnitude of the white number will never change, but sometimes the type of damage may vary if it’s a caster weapon.