When first doing research about Guangxu, I noticed that a lot of the photos online that claim to be Guangxu, did not look alike. Having photos or even portraits of Chinese nobility made available to the public was not allowed, so it is understandable why it was difficult for those outside the court to be sure what he actually looked like.

Then, I found the work of Charles Jacotin. He was a very well-known 19th century portrait artist, and as the link below shows, had created portraits of many notable Europeans. Pearl was known to have brought photographers into the Forbidden City, one of the many things she did that annoyed the traditionalists. Therefore, Jacotin would have certainly had a photo of Guangxu on which to base his portrait.

The portrait of Guangxu by Jacotin is likely the best and most accurate likeness of Guangxu that is available, at least among those circulating publically. As for why there are so many misrepresentations of his likeness still being used today, even officially, one can only guess.

Jacotin's work: link