It’s completely normal for babies to go up to 5 days without pooing. My 3 month old has recently been going 2 days without pooing and then I get a nice big poo on the third day and then he will usually poo a couple times that day. If he’s really struggling through, we give him an ounce of water which helps flush x
Our baby is now going sometimes 3/4 days without popping, said to our gp last week about it and they said it’s normal around this age and as long as it’s still loose and not hard balls when they do poop it’s not constipation and perfectly fine x