Level modiefiers work both ways. Too low, we do reduced damage. Too high, we do reduced damage. Level cap starts getting significant at 2 level difference and grows more and more dramatic with each level, up to 8 level difference. So for a level 30, all enemies between level 1-22 are the same level of difficulty (easy), but things after that get progressively harder. For a 29, a 24 enemy is still well within the prime range of modifiers, and damage is reduced enough to make us seem comparable to level 24 guardians, with the significant differences coming from our weapon's actual upgraded levels of damage more so than our higher level. Hope that makes sense.