saying bad things to your baby

My MIL comes visit once a week and she talks nonsense to my baby all the time, even did not want to acknowledge that my baby is calling out for me. I don't get why she's jealous of my baby being close to me🤷🏻‍♀️I would first tell my baby what grandma said is not true and tell my mil off. Babies may seem too young to understand but in fact whatever the adults say would affect them.