As my MRE, I've got the following file:
blah.py
'''Blah module'''
import pydantic
class Foo:
    '''Foo class'''
    class Bar(pydantic.BaseModel):
        '''Bar class'''
        x: str = pydantic.Field(description='The x.')
        @pydantic.validator('x')
        def do_nothing(cls, value: str) -> str:
            return value
I'm attempting to use Sphinx to generate documentation for this module. In my conf.py, I have
extensions = [
    'sphinx.ext.autodoc',
    'sphinxcontrib.autodoc_pydantic',
]
My blah.rst is
Blah
====
.. automodule:: blah.blah
    :members:
I've pip installed pydantic and autodoc_pydantic.
However, when I make html, I get
Exception occurred:
  File "/home/user/Projects/Workspace/env/lib/python3.10/site-packages/sphinxcontrib/autodoc_pydantic/inspection.py", line 311, in __init__
    self.attribute: Dict = self.model.Config
AttributeError: type object 'Foo' has no attribute 'Config'
It appears that autodoc_pydantic thinks that Foo inherits from pydantic.BaseModel when it's really Bar that does.  If I remove 'sphinxcontrib.autodoc_pydantic' from extensions, the error goes away.
More interestingly, if I delete the validator, the error goes away as well.
autodoc_pydantic is version 1.6.1.