3 month old- refusing to feed

Hi mummies! My baby is turning 3 months in 3 days. These last 2 wks I noticed his hunger has reduced hence feeding frequence also changed from every 2 hrs, suddenly 4 or more hours. I’m just worried because he is suppose to eat more when growing instead of decreasing right? By the way, he is on formula. He seems to be happy and not fussy. It’s just that it’s a sudden decline of milk intake. When he was 2 month old he is drinking 3-3.5 oz every 2 hrs. Now he will drink the same but after every 4-5 hrs. If I give him early he will get fussy. #worryingmom #formula #advicepls