I think it's because that's condition overrides in paperdoll.lua

registerConditions = function(self, condition)
    **condition:RegisterCondition("level", false, self.getLevel)**
    condition:RegisterCondition("specialization", false, self.isSpecialization)
end,

Also relativelevel() returns wrong value in timewalking dungeons
I think it's because no UnitEffectiveLevel() checking in this function

Can you clarify what you are trying to do? target.Level()?

For example:

AddFunction IsBigGuy { target.RelativeLevel()>0 or (target.RelativeLevel() == 0 and (target.Classification(elite) or target.MaxHealth()>{player.MaxHealth()*2})) }

I do not uses target.Level() but this function exists and would be usable

This code doesn't exist anymore, are you sure that the bug is still there?