import asyncio
from google.auth._default_async import default_async
from google.auth.transport import _aiohttp_requests


async def main():
    creds, project = default_async()
    await creds.refresh(_aiohttp_requests.Request())
    print('Credentials:', creds)
    async with _aiohttp_requests.AuthorizedSession(creds) as authed_session:
        response = await authed_session.request('POST', 'https://example.org'))
        print(response.json())


asyncio.run(main())

Credentials: <google.oauth2._credentials_async.Credentials object at 0x7fc2e3ea9f10>
...
  File "/usr/local/lib/python3.11/site-packages/google/auth/transport/_aiohttp_requests.py", line 333, in request
    await self.credentials.before_request(
TypeError: object NoneType can't be used in 'await' expression