From what I understand, this is something a German tabloid speculated on and the world ran with it. There’s currently no evidence this actually happened.
“This wild rumor started off a few weeks ago from pure hearsay,” FIS spokesperson Bruno Sassi told The Associated Press. “There has never been any indication, let alone evidence, that any competitor has ever made use of a hyaluronic acid injection to attempt to gain a competitive advantage.”
From what I understand, this is something a German tabloid speculated on and the world ran with it. There’s currently no evidence this actually happened.
ESPN article on the controversy