`Self` type doesn't work on attributes

[DetachHead]

from typing import Self, ClassVar

class Foo:
    instance: ClassVar[Self]
    
    @classmethod
    def get_instance(cls) -> Self:
        return cls.instance # error: Incompatible return value type (got "Foo", expected "Self")  [return-value]
    
    @classmethod
    def get_instance2(cls) -> Self:
        return cls.get_instance() # no error

playground