Why do some listings on mobile come out in desktop format?

I have noticed recently that while browsing on the mobile app, a number of listings take longer to load and are displayed in the desktop format, complete with the email reminder setting and different UI. It seems to be inconsistant, as some new listings are normal while others are changed. Does anyone know why this is? If it is an update, what is the point of replacing the tried and true mobile listing pages with the overbearing desktop one clearly made for larger screens, but more importantly why apply it at random?