Oh, I don't know. If we can label "accidentally using the wrong scope" as a human error, I could easily see a situation where someone meant to remove something from Chinese search results but accidentally did it worldwide. I don't know what their infrastructure is like, what kind of safeguards they have in place, or even what they do to block a result from the all-seeing algorithm. Which is more likely: that Microsoft would allow China to dictate what the rest of the world can/cannot see or that someone made a mistake and blocked something globally instead of regionally?
However although you don’t intentionally make a mistake, you do intentionally carry it out.
In that case, no amount of safety checking will stop a human being from implementing bad logic.
Human error knows no bounds.
Did they? https://www.bing.com/images/search?q=tank+man has no results of Tank Man. https://imgur.com/a/U5fDs7P (If you do see Tank Man images, see the edit at the end of this comment.)
If you press enter on the search box with the pre-filled "tank man", then you get a URL with more query-string parameters - https://www.bing.com/images/search?q=tank+man&imgurl=&cbir=s... , and that page does contain the actual Tank Man.
Seems it can be narrowed down to the form= parameter. https://www.bing.com/images/search?q=tank+man&form=QBILPG has Tank Man, without the form= it doesn't. The actual value of the form= parameter doesn't value either, as long as it's not empty.
I have no idea what they're doing in the backend.
Edit: Another weird thing - https://www.bing.com/images/search?q=tank+man with JS enabled redirects to a different page with additional querystring parameters, and this page does have Tank Man. My testing above was done with JS disabled, which is why I got the pre-redirect page that doesn't have his pictures.
>I have no idea what they're doing in the backend.
The pagination theory doesn't make sense to me though. The relevant parameter is called "form", its actual value doesn't matter as long as it's non-empty, and surely a sane implementation would treat the lack of a page parameter as page 1 and not page whatever-the-stormtrooper-image-is-on.
Then Microsoft manually took an action to restore the image results in Bing for the query "tank man." Which then filtered down to DDG since it relies on Bing (previously DDG's image results were similarly devoid of the proper results).