You may want to find out is your LO allergic to cows' milk first. https://www.nhs.uk/common-health-questions/childrens-health/what-should-i-do-if-i-think-my-baby-is-allergic-or-intolerant-to-cows-milk/#:~:text=Cows'%20milk%20allergy%20can%20cause,a%20runny%20or%20blocked%20nose
I have heard some babies are allergic to formula milk. but not all the kids.