Why does PyCharm give a warning here?

I have some code here, which throws a warning about an instance attribute being defined outside of __init__, shouldn't that warning be supressed by default if @property/@x.setter decorated is used?

class A:
    def __init__(self, x):
        self.x = x

    @property
    def x(self):
        return self._x

    @x.setter
    def x(self, value):
        self._x = min(1000, value)  # Instance attribute __x defined outside __init__

a = A(9999)
print(a.x)  # -> 1000