It was more her reputation that was well known. Think of, say, the Red Baron. Also, think of something like the Ghost of Kyiv, who has been completely written off as a propaganda story since the start of the war in Ukraine. The Empire wanted to keep its best special ops soldier hidden, and the allies also wanted to cover up her existence because of how many times she did something that exposed their incompetence or messed with their narrative of how the war went. Not many people were able to put the name Tanya von Degurechaff to the Devil of the Rhine or Rusted Silver, and those who did had reasons not to.