should mypy recognize pep-681 @dataclass_transform on a method as well as a function?

Just noticed that trying to make an object method provide @dataclass_transform functionality is not recognized by mypy as a pep-681 use of @dataclass_transform (it does not complain either, just silently ignores it):

from typing import dataclass_transform

class SomeClassThing:
    @dataclass_transform()
    def make_a_dataclass(self, cls: type) -> type:
        return cls

sct = SomeClassThing()

@sct.make_a_dataclass
class MyClass:
    x: int
    y: str

m1 = MyClass(x=5, y="y")

mypy:

test4.py:16: error: Unexpected keyword argument "x" for "MyClass"  [call-arg]
test4.py:16: error: Unexpected keyword argument "y" for "MyClass"  [call-arg]
Found 2 errors in 1 file (checked 1 source file)

the above would need to be reorganized like this:

from typing import Callable
from typing import dataclass_transform

class SomeClassThing:
    pass

@dataclass_transform()
def make_a_dataclass(sct: SomeClassThing) -> Callable[[type], type]:
    def decorate(cls: type) -> type:
        return cls
    return decorate

sct = SomeClassThing()

@make_a_dataclass(sct)
class MyClass:
    x: int
    y: str

m1 = MyClass(x=5, y="y")

where mypy is happy:

Success: no issues found in 1 source file

SQLAlchemy has a pep-681 feature that mostly uses the superclass approach, however we also offer a decorator that looks like @mapper_registry.mapped_as_dataclass(), and I just noticed that while pyright has always accepted this, mypy does not. So I'm adding an alternative decorator of the above form @mapped_as_dataclass(mapper_registry). Took a look at pep-681 and it discusses @dataclass_transform applied to a function or a class, not a method. So I'm out of luck. but it seems ....like it should work? pyright does it....

Start with the method-based reproducer in the issue and read PEP 681's rules for where @dataclass_transform may be applied. Compare the behavior with the function-based example and pyright, then determine whether method support is specified; done means mypy consistently handles the decorator or clearly rejects the unsupported form.