Enfamil newborn vs infant

So baby girl is one month old and we just switched to the infant formula from newborn. Now she suddenly cannot finish a bottle and is constantly falling asleep. We have been on the infant for 2 days max. Is this just a growth spurt making her more sleepy or do I need to be concerned about the fact that she is refusing to finish bottles.

She drinks usually anywhere between 3-4 oz every three hours. Currently I am lucky if she finishes two ounces.

I just didn't know if this is connected to the new formula or just a weird coincidence.