Gunicorn: UndefinedTable: relation "user" does not exist

Here is the scenario, I’m deploying the Django app on an ec2 instance. I’m following this guide Digitalocean deployment guide. when I run my app using python manange.py runserver 0.0.0.0:800 and access the admin portal via http://server-ip-address:8000. everything works fine.
But when I run gunicorn --bind 0.0.0.0:8000 apbackend.wsgi and try to access the admin page it gives me 500 server errors and exception:

UndefinedTable: relation "user" does not exist
LINE 1: ...r", "user"."is_staff", "user"."is_superuser" FROM "user" WHE...

Setting.py

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'rest_framework_simplejwt.token_blacklist',
    'rest_framework_simplejwt',
    'corsheaders',
    'drf_yasg',
    'django_extensions',
    'src',
    'communications',
    'rest_framework',
    'registration',

]
MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'corsheaders.middleware.CorsMiddleware',
    # 'django.contrib.auth.middleware.AuthenticationMiddleware',
    
    
]

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': os.environ.get("DATABASE_NAME"),
        'USER': os.environ.get("DATABASE_USER"),
        'PASSWORD': os.environ.get("DATABASE_PASSWORD"),
        'HOST': os.environ.get("DATABASE_HOST"),
        'PORT': '5432',
    }
}

WSGI_APPLICATION = 'apbackend.wsgi.application'
AUTH_USER_MODEL = 'registration.User'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [BASE_DIR / 'templates'],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]

REST_FRAMEWORK = {
    'DEFAULT_PERMISSION_CLASSES': (
        'rest_framework.permissions.IsAuthenticated',
        'rest_framework.permissions.IsAdminUser'
    ),
    'DEFAULT_AUTHENTICATION_CLASSES': (
        'rest_framework_simplejwt.authentication.JWTAuthentication',
        'rest_framework.authentication.SessionAuthentication',
        'rest_framework.authentication.BasicAuthentication',
        'rest_framework.authentication.TokenAuthentication',

    ),
}

registration.models.py

from django.db import models

# Create your models here.
import uuid

from django.db import models
from django.contrib.auth.models import PermissionsMixin
from django.contrib.auth.base_user import AbstractBaseUser
from django.utils import timezone

from .managers import CustomUserManager

from rest_framework_simplejwt.tokens import RefreshToken

AUTH_PROVIDERS = {'facebook': 'facebook', 'google': 'google',
                  'twitter': 'twitter', 'email': 'email'}
# Create your models here.

class User(AbstractBaseUser, PermissionsMixin):
    # These fields tie to the roles!
    A = 1
    I = 2
    C = 3

    USER_ROLE = (
        (A, 'A'),
        (I, 'I'),
        (C, 'C')
    )

    # Roles created here
    uuid = models.UUIDField(unique=True, editable=False, default=uuid.uuid4)
    username = models.CharField(max_length=255, unique=True, db_index=True)
    email = models.EmailField(unique=True)
    first_name = models.CharField(max_length=50, blank=True)
    last_name = models.CharField(max_length=50, blank=True)
    role = models.PositiveSmallIntegerField(choices=USER_ROLE, blank=True, null=True)
    date_joined = models.DateTimeField(auto_now_add=True)
    is_verified = models.BooleanField(default=False)
    is_active = models.BooleanField(default=True)
    is_deleted = models.BooleanField(default=False)
    created_date = models.DateTimeField(default=timezone.now)
    modified_date = models.DateTimeField(default=timezone.now)
    auth_provider = models.CharField(
        max_length=255, blank=False,
        null=False, default=AUTH_PROVIDERS.get('email'))
    is_staff = models.BooleanField(default=False)
    is_superuser = models.BooleanField(default=False)

    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = ['username', 'role']

    objects = CustomUserManager()

    class Meta:
        db_table = 'user'
        verbose_name = 'user'
        verbose_name_plural = 'users'

    def __str__(self):
        return self.email

    def save(self, *args, **kwargs):
        self.is_staff = True if self.role == self.ADMIN else False
        self.is_superuser = True if self.role == self.ADMIN else False
        super(User, self).save(*args, **kwargs)

    def tokens(self):
        refresh = RefreshToken.for_user(self)
        return {
            'refresh': str(refresh),
            'access': str(refresh.access_token)
        }

I have spent a lot of time debugging this. still haven’t found anything.