Why does the price keep changing when I try and book?

I’m trying to book an all inclusive trip for my family & I. 2 adults, 1 child who is 5.

When I search Dreams Onyx Punta Cana the price returns as $2089 per adult including taxes and fees (Canadian) and approx. $800 for the child. Including taxes and fees. This is for mid November.

When I hit “book now” the price on the next page jumps to $2489 per person, while the child’s price remains the same. If I remove the child, the price goes back to $2089. At first I thought they were adding the child’s cost to the adult prices, but that’s not the case as the adult price jumps, while the child’s cost remains.

I book 2 trips per year and have never had this happen.

Can anyone offer any insight as to why?