My daughter has not wanted to finish her bottles: Advice?

Hello, so recently my daughter hasn’t been wanting to finish her bottles, she drink 6 oz, three scoops of formula and it’s always warm. Nothing has changed about her feeding but she doesn’t want to finish them anymore and sometimes moves her head back and forth cause she doesn’t want anymore or she just starts crying while drinking it. She is 6 months old so I was just wondering if anyone else has this problem or if a normal thing kids do? If there’s anything I can do to make her want to finish it. Formula cost alot and she wants to eat more often cause she doesn’t finish her bottle