A ton of creatures are flat out immune to frightened.
Which conditions are the most monsters immune to, and which are the fewest immune to?
Oozes, most constructs, a lot of undead, plants, and fiends can’t be frightened at all.
You also have the save to deal with (and legendries) and the fact without the frightened effect the damage is piddling, plus the fact it uses your concentration slot, and only targets one creature.
I still think it's a typo (it should be a Save and not an Ability check, and that's how I would rule it in my game) but even with the typo, it's situationally strong, without being broken.