Instead of checking if it contains invalid characters (your code only checks if it contains uppercase letters and there are more than only those) check if all chars of the string are valid.

yes but when i delete the space in test section the username is still returning False and i add space different usernames and they are return True value

There is a space there, spaces are not allowed characters, are they?

in python solutions => why is this username should be ("asd43 34") False ? i think it should be True there are no not allowed characters and length is between 4 and 16