Daughter isn’t liking whole milk?

So last night I gave her the whole milk itself since she finished her formula and she almost finished it, only left 2 ounces out of 6. She’s been doing fine before when I was mixing it with both milk and formula. But today she didn’t take her 6 ounces in the morning and only took 2 ounces for her afternoon bottle . I don’t know if it’s her not liking the milk or her not liking her sippy cup ( which she was taking fine yesterday throughout the whole day ) idk what to do :( any advice!!!? Thank you.