Re-using sqlalchemy.dialects.postgresql.UUID instance generates mypy violation

[mtvx-o]

Describe the bug

Storing an instance of sqlalchemy.dialects.postgresql.UUID to a variable and re-using that in the column declarations is seen as NullType.

Expected behavior

Type should be detected as Column[UUID]?

To Reproduce

from typing import Optional
from uuid import UUID

from sqlalchemy import Column
from sqlalchemy.dialects.postgresql import UUID as PostgresUUID
from sqlalchemy.orm import declarative_base

PgUUID = PostgresUUID(as_uuid=True)
Base = declarative_base()


class Foobar(Base):
    __tablename__ = "foobar"

    works: Optional[UUID] = Column(PostgresUUID(as_uuid=True))
    doesnt: Optional[UUID] = Column(PgUUID)

Error

Running with sqlalchemy.ext.mypy.plugin enabled in mypy configs:

$ mypy foobar.py
foobar.py:15: error: Incompatible types in assignment (expression has type "Column[NullType]", variable has type "UUID")  [assignment]
Found 1 error in 1 file (checked 1 source file)

Versions.

• OS: Linux
• Python: 3.9.9
• SQLAlchemy: 1.4.39
• mypy: mypy 0.971
• SQLAlchemy2-stubs: 0.0.2a25

[mtvx-o]

Also construction gives violation:

Foobar(
    works=uuid.uuid4(),
    doesnt=uuid.uuid4(),
)

$ mypy foobar.py
...
foobar.py:20: error: Unexpected keyword argument "doesnt" for "Foobar"  [call-arg]
...