Baby sleeps longer after sending to infant care

Anybody’s baby sleep more/longer after sending to IFC? Idk what theyre tired from 😂 and he’s only 2.5months. I realised after baby started IFC, he tend to sleep longer after school. Like i would pick him up at 5 or so, after his milk at 5+ or 6pm, he would play abit then gets sleepy then sound asleep until very early morning 2/3am or even can go until 5+am then wake up for milk. Technically didnt ask for milk for 12hrs and sleep for like 10hrs or so. Is this normal? Cause based on his weight, he should be drinking 800+ml a day but now only 600ml since he skip alot of night feeding time. Im scared he would be dehydrated or malnutrition. Altho he’s still gaining weight and doesn’t look like in pain or anything. I dont wish to increase his milk intake just yet as im scared he would puke out alot. He’s drinking 120ml/2.5 - 3hrs during the day. Cause prev before starting IFC, he would go longer stretch of sleep at 8-11pm. Then would wake up every 3-4hrs for milk.