Conftest.py is not loaded from a subfolder

The thing is that I need to have a conftest with a special setting for a set of tests. To use a live database in readonly mode only for these tests. Other tests from unit folder working with an empty db created by pytest. If I run pytest tests or pytest tests/unit conftest from tests_readonly_db are not recognized. It is recognized when I put conftest file in unit folder. And run any of these two commands. But it works perfectly when I run pytest tests/unit/tests_readonly_db with conftest in tests_readonly_db folder. Also tried to creat another subfolder in tests_readonly_db, put tests in there, with conftest.py staying level up. Doesn't work.

I wonder if there is way to implement desired behaviour. Found some related answers, but couldn't fully understand how it helps in my case. For example: https://stackoverflow.com/a/13686206/7744657

But if

conftest.py files from sub directories are by default not loaded at tool startup.

Why it was loaded from a unit folder?

conftest.py

import pytest


@pytest.fixture(scope='session')
def django_db_setup():
    """Avoid creating/setting up the test database"""
    pass


@pytest.fixture
def db_access_without_rollback_and_truncate(request, django_db_setup, django_db_blocker):
    django_db_blocker.unblock()
    request.addfinalizer(django_db_blocker.restore)

App structure: