Weird sag on belly , is this normal

Can someone please tell me is this is normal or not, my stomach started doing this around january .. I’m 39 weeks today and my belly sags even with my baby still in my tummy and when I touch it it’s hard and when I press on it slightly leaves pressure marks as if I had memory foam in my belly .. please help .. I had this same issue with my previous pregnancy with my daughter in 2018.