The flavoring was banned because studies had shown that high does of safrole (found inside the sassafras root) could lead to health issues in laboratory rats, specifically liver cancer.
However, some argue that this ban may have been overly cautious as consuming the amount needed to pose a risk is highly unlikely. When comparing taste, YouTuber LabCoatz ranks it a 7 out of 10, stating he likely could not tell the difference between this and popular brands like A&W root beer.
Via LabCoatz.