And you a lie. You have never heard of a vegan
baby.
Unless they were trying to starve their child.
There is no alternative to breast milk or formula when it comes to feeding infants. We're not talking about when they are 6 months + or toddlers and can start eating different foods.
https://www.parents.com/baby/feeding/nutrition/how-to-raise-a-vegan-baby/Registered dietitian
Kaleigh McMordie, MCN, RDN, LD recommends adding on more months to your breastfeeding cycle if you'll be raising your baby vegan."Vegan infants may need to be breastfed longer than non-vegans since breast milk is such a great source of nutrients," she says. "Wean your child to soy milk fortified with vitamins B12 and D to ensure he gets additional fortification in those key nutrients. Avoid other plant-based milks due to their lack of protein." (Note that babies shouldn't drink any milks—including plant-based—as a primary beverage before 12 months. Before that stick with breast milk or formula.)