Sqlalchemy subquery is cached, the result is incorrect respect to the different parameters

main.py

from sqlalchemy import create_engine, select, func, text
from sqlalchemy.orm import sessionmaker, declarative_base
from sqlalchemy import Column, Integer, Date
import datetime

#SQLAlchemy==1.4.23 psycopg2==2.9.1 with postgresql 13
engine = create_engine("postgresql+psycopg2://postgres:[email protected]:5432/sa_test?sslmode=disable", echo=False)
Session = sessionmaker(engine)

Base = declarative_base()

class CalendarDate(Base):
    __tablename__ = 'calendar_date'

    dt = Column(Date, primary_key=True)
    value = Column(Integer)


Base.metadata.create_all(engine)

def prepare_test_data(n: int):
    today = datetime.datetime.today()

    with Session() as session:
        session.query(CalendarDate).delete()

        for i in range(n):
            _date = today - datetime.timedelta(days=i)
            session.add(CalendarDate(dt=_date, value=i))
        session.commit()

if __name__ == '__main__':
    prepare_test_data(100)

    offsets = [5, 15, 30]

    for offset in offsets:
        with Session() as session:
            sub_stmt = select(CalendarDate).where(
                CalendarDate.value < 1000
            ).order_by(CalendarDate.dt.desc()).limit(offset).subquery

            stmt = select(func.min(text("dt"))).select_from(sub_stmt)

            print(session.execute(stmt).scalars().one_or_none())

            # output is the same, offset is cached
            # 2021-09-12
            # 2021-09-12
            # 2021-09-12