And it does it in an unusual way. After browsing around on the website and then noticing that the back button history is just the same site name repeated many times, I worried about my history needlessly polluted by this website. But when I opened my browser history, it was just a handful of URLs in there, each representing the screenshot I had actually clicked on.

So, yes, it does break the back button, but it doesn't pollute the actual history.

This is so odd. How is the entire history stack populated with 1 entry?