This product has A LOT of preservatives in it: phenoxyethanol, methylparaben, propylparaben, butylparaben and isobutylparaben. Some parabens are safe to use up to certain concentration, and they are some of the most effective and researched preservatives. So they should be safe, but I just don't see the point of using every single one of them in a product like this.
BUT. Isobutylparaben was previously listed as a preservative ingredient in the Annex V of European Cosmetic Regulation, which is a list about preservatives allowed to use in cosmetics. So, basically, this lash serum has an ingredient that's banned in Europe. To my knowledge it's permitted to use in cosmetics in Korea hence this product containing it, but I would avoid using this lash serum since there is no information on the possible risks of this ingredient.