Recently Added Photos are displayed in Descending Date Order

"Descending date order" typically means newest images first at the top, and oldest images last, at the bottom. That's the way that "Recently Added" should list the images, but I think there's a bug which causes the list to get mixed up, with stuff randomly out of order. Maybe that's what you're experiencing, if so the fix should simply be to select the Recently Added entry, then exit the app while it is still selected. On restart the order should be "normal", though of course you'll be at the previous position in the list so will have to scroll up to get back to the top.