Some breeds have extra toes.
What kind if chicken do you have
Here is an article showing some of the breeds.
https://www.google.com/url?sa=t&source=web&rct=j&url=https://petkeen.com/chicken-breeds-with-5-toes/&ved=2ahUKEwi2lvDO5fLwAhWUB80KHRuqAr4QFjAKegQIEBAC&usg=AOvVaw2kuyJYvK-s3nl13yXzqJOv