The screenshot below shows what I see at the bottom of all of my Pinterest boards as of a couple days ago. Above the light gray divider line you can see the photos that I have pinned on one of my private boards called "Make for Lorraine". Below that line it says "More ideas for this board" and there are thousands of photos that I have NOT pinned on that board. They appear automatically and they are totally random photos. When I scroll through those pins they go on forever. There is no end because more and more load whenever I scroll.
The screenshot below shows what I see when I go to anyone else's boards. There is that "P" icon at the very bottom of the page and there are no extra pins that the pinner didn't add to that board like I see on mine. That board belongs to one of my friends. I asked her if she sees the divider line and "More ideas for this board" at the bottom of any of her boards and she told me that she does not see that, only the "P" icon at the bottom.