I don't know if it is a bug or a feature but the result seems to be
wrong for me: A constructor argument remembers its values from the last call

Yes, this is expected. Default values are only evaluated once, at
function creation time. If you need to have a mutable default argument
that is assigned to something and changed, use something like this:

def f(arg=None):
    if arg is None:
        arg = []
    ...