Lactic acid is a naturally occurring substance that bacteria produce during fermentation. It acts as a pH regulator and preservative however does not contain dairy itself, despite it's latin root ("lac" meaning milk). It can be found in many dairy-free and/or vegan foods.
There is not enough evidence to conclude that lactic acid poses no health effects since it acts as a preservative, additive, extends shelf life, inhibits food discoloration, and more.
Is Lactic Acid Vegan?https://www.medicalnewstoday.com/articles/is-lactic-acid-vegan#what-it-is
Health Benefits of Lactic Acid Bacteria (LAB) Fermentateshttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC7352953/
Why is lactic acid put in food?https://www.medicalnewstoday.com/articles/lactic-acid-in-food#why-is-it-put-into-food