Why custom clients might be ignored by unittest in Django?

Question

Exploring Unittest, can't figure out why these tests ignore custom clients prepared in setUp() method and use the built-in self.client (== self.guest_client). Thus only the last test for anonimous user works properly. The same setUp() method works fine in other test files, as well as url constants.

test file:

User = get_user_model()

NOTE_SLUG = 'note-slug'
HOME_URL = reverse('notes:home')
LOGIN_URL = reverse("users:login")
SIGNUP_URL = reverse('users:signup')
LOGOUT_URL = reverse('users:logout')
NOTES_LIST_URL = reverse('notes:list')
ADD_NOTE_URL = reverse('notes:add')
NOTE_CONFIRM = reverse('notes:success')
NOTE_URL = reverse('notes:detail', args=(NOTE_SLUG,))
NOTE_EDIT_URL = reverse('notes:edit', args=(NOTE_SLUG,))
NOTE_DELETE_URL = reverse('notes:delete', args=(NOTE_SLUG,))


class TestRoutes(TestCase):
    @classmethod
    def setUpTestData(cls):
        cls.url_list = (
            HOME_URL,
            LOGIN_URL,
            SIGNUP_URL,
            LOGOUT_URL,
            NOTES_LIST_URL,
            ADD_NOTE_URL,
            NOTE_CONFIRM,
            NOTE_URL,
            NOTE_EDIT_URL,
            NOTE_DELETE_URL
        )
        cls.author = User.objects.create(username='author')
        cls.note = Note.objects.create(
            title='Заголовок',
            text='Текст заметки',
            slug='note-slug',
            author=cls.author,
        )

    def setUp(self):
        self.guest_client = Client()
        self.reader = User.objects.create(username='reader')
        self.authorized_client = Client()
        self.authorized_client.force_login(self.reader)
        self.author_client = Client()
        self.author_client.force_login(self.author)

    def test_pages_for_author(self):
        for url in self.url_list:
            with self.subTest(url=url):
                response = self.author_client.get(url)
                self.assertEqual(response.status_code, HTTPStatus.OK)

    def test_pages_for_auth_reader(self):
        for url in self.url_list[0:7]:
            with self.subTest(url=url):
                response = self.authorized_client.get(url)
                self.assertEqual(response.status_code, HTTPStatus.OK)
        for url in self.url_list[7:10]:
            with self.subTest(url=url):
                response = self.authorized_client.get(url)
                self.assertEqual(response.status_code, HTTPStatus.NOT_FOUND)

    def test_pages_for_anonymous(self):
        for url in self.url_list[0:4]:
            with self.subTest(url=url):
                response = self.guest_client.get(url)
                self.assertEqual(response.status_code, HTTPStatus.OK)
        for url in self.url_list[4:10]:
            with self.subTest(url=url):
                redirect_url = f'{LOGIN_URL}?next={url}'
                self.assertRedirects(self.guest_client.get(url), redirect_url)