Google OAuth RefreshError even with Refresh Token present in the Django app

My app running on Django with Django allauth allows signup/login only via Google OAuth. Therefore when a user is registered, his social oauth details are saved to All-auth Social Accounts model and the token data saved in Social Application Tokens model.

We want the users to be logged-in as long as possible, without granting/revoking access regularly.

Question 1: The default expiry is set as 1 hour from the registration time. How can I extend this programmatically and for how long (can it be never-expire?)

Currently, a user logged in at 5:00 and I get the following data from credentials.to_json():

{
"token": "ya29.A0ARrdaM8YXPM35RXPv7UK-pXLZvWG49T-MgCZ5wMse2ADMXOZJOWFJKMaq1PkobADLptM5YX5mnrliS2yCCESqCk0NTaZJkfe6inK94j6WQMFZWIT_xRyBTOX4W3dUEiuLhHFpQcD5vS-x_Y22pUzxwgI23pp",
"refresh_token": "1//0gYC8oucHhTBVCgYIARAAGBASNwF-L9IrCG7c5IJCBMVznUrytGEFsJbsObAFvmNBoQbHHGA1KESyBWgmudEVogbes8ski87q_5g",
"client_id": "blablabla.apps.googleusercontent.com",
"client_secret": "xyzsecret"}

No other data is returned.

At 6:05, the credentials.to_json() is exactly the SAME AS ABOVE. But to fetch any Google/Youtube API data, I get the following error in server logs:

google.auth.exceptions.RefreshError: The credentials do not contain the necessary fields need to refresh the access token.

Question 02: When there's a Refresh Token available already, why the error? As per the docs, it refreshes the token automatically few minutes before the expiry. What am I missing?

I already had "access_type": "offline" in the providers settings. I also tried adding "prompt": "consent", but no effect.

Django Settings:

INSTALLED_APPS = [
    "allauth",
    "allauth.account",
    "allauth.socialaccount",
    "allauth.socialaccount.providers.google",
    ...
]

AUTHENTICATION_BACKENDS = [
    "django.contrib.auth.backends.ModelBackend",
    "allauth.account.auth_backends.AuthenticationBackend",
]

SOCIALACCOUNT_PROVIDERS = {
    "google": {
        "SCOPE": [
            "profile",
            "email",
            "https://www.googleapis.com/auth/youtube",
            "https://www.googleapis.com/auth/youtube.readonly",
            "https://www.googleapis.com/auth/youtube.upload",
            "https://www.googleapis.com/auth/youtube.force-ssl",
        ],
        "AUTH_PARAMS": {
            "access_type": "offline",
            "prompt": "consent",
        },
    },
}

And the Django Views snippet related to OAuth:

import googleapiclient.discovery
import googleapiclient.errors
from allauth.socialaccount.models import SocialAccount, SocialApp
from google.oauth2.credentials import Credentials

def get_credentials_google(user):
    app_google = SocialApp.objects.get(provider="google")
    account = SocialAccount.objects.get(user=user)
    user_tokens = account.socialtoken_set.first()
    creds = Credentials(
        token=user_tokens.token,
        refresh_token=user_tokens.token_secret,
        client_id=app_google.client_id,
        client_secret=app_google.secret,
    )
    return creds

def get_youtube_account(user):
    api_service_name = "youtube"
    api_version = "v3"
    credentials = get_credentials_google(user)
    youtube = googleapiclient.discovery.build(
        api_service_name, api_version, credentials=credentials
    )
    return youtube

def get_youtube_videos(request):
    youtube = get_youtube_account(request.user)
    request = youtube.liveBroadcasts().list(
        part="id, snippet, contentDetails, status",
        broadcastStatus="completed",
        broadcastType="all"
    )
    response = request.execute()
    return response

Note: There's no front-end framework I'm using django with django template UI.