Decreased formula intake?

Hi,

My baby is 4 month old and she suddenly started to decrease milk intake. No infection, no cold, no fussing, nothing.

She was used to drink 160-180ml at a time (6-7oz) now she drinks half of that.

Tomorrow we have an appointment because of that, yet I wanted to ask you if you have experienced something like that when your baby was around 4month?

She went through 4 month sleep regression, I could definitely tell it. But it has passed and after about 1 week she started to eat less.

Any thoughts?