According to the notes, “This update provides important bug fixes and addresses a rare issue where photos that experienced database corruption could reappear in the Photos library even if they were deleted.”
The supposedly-deleted photos popping to the top of user’s “recent” photos included nude pictures in some cases, and at least one person reported they reappeared on an iPad that had been erased and sold to someone else.
Users should obviously install the update ASAP, however it’s unclear how many people may be at risk of experiencing this, which images are likely to reappear, or what you can do about a device that’s no longer in your control. The Verge has reached out to Apple for a comment on the issue and we will update this article if we receive a response.