As you know, Google warned and then launched the Google App Install Interstitial penalty in early November. The purpose was to provide a better experience for mobile searchers.
But the Google Photos team doesn't agree, I guess. They are using full screen app install interstitials ads when you try to view a photo hosted on Google Photos. In fact, Eric Wu spotted it when doing a search in Google, on his mobile device, then clicking from the search result to Google Photos. He posted this on Twitter and shared a screen shot.
This is what he saw after clicking on the Google Photos link from Google's mobile results:
This is exactly the experience Google's search team is looking to avoid. So what went wrong? Potentially Google is testing showing some the app install interstitials and some not? I am not sure but this is not a good experience.
Eric Wu asked, in a sarcastic manner, "So I went to Google Photos from search and saw this .... Does that count as an interstitial?"
Forum discussion at Twitter.