2014: Bing has been filtering out both English and Chinese language search results for politically-sensitive terms such as "Dalai Lama" and "Tiananmen" [0]
[0] https://www.zdnet.com/article/microsoft-denies-accusations-o...
As other commenters said, may be it's intentional but the change was supposed to be visible only inside China and then someone messed up and it leaked to search results outside of China. (for example : a bad update to the rule censoring the subject inside china made it visible worldwide)
For me, it seems unlikely that they did it on purpose. not because they are good but because no company wants this kind of publicity.