How to access yahoo mailbox imap using oauth2?

Question

I am trying to access yahoo mailbox, I have created a yahoo application for the same purpose. After allowing permission to access mailbox, I have access_token and refresh_token for oauth.

I am trying to authenticate using imaplib and I always get authentication failed error.

This is the piece of code I wrote, while I can refresh the auth_tokens, I havent been able to access the mailbox so far

import base64
from oauthlib.oauth2 import BackendApplicationClient
from requests.auth import HTTPBasicAuth
from oauth2.clients.imap import imaplib

USERNAME = 'XXX'

# imap settings
IMAP_SERVER = 'imap.mail.yahoo.com'
IMAP_PORT = 993

# application secrets
client_id = 'XXX'
client_secret = 'XXX'

authorization_base_url = 'https://api.login.yahoo.com/oauth2/request_auth'
token_url = 'https://api.login.yahoo.com/oauth2/get_token'

refresh_token = 'refresh token...'

client = BackendApplicationClient(client_id=client_id)
oauth = OAuth2Session(client=client)
token = oauth.refresh_token(token_url, refresh_token=refresh_token, auth=HTTPBasicAuth(client_id, client_secret))
access_token = token['access_token']

mail = imaplib.IMAP4_SSL(IMAP_SERVER, IMAP_PORT)

auth_string = base64.b64encode(f'\x00{USERNAME}\x00{access_token}'.encode()).decode()

mail.authenticate('XOAUTH2', lambda x: auth_string)

# I get imaplib.IMAP4.error: AUTHENTICATE command error: BAD [b'[AUTHENTICATIONFAILED] AUTHENTICATE Invalid credentials']


mail.select('inbox')

Right after, mail.authenticate('XOAUTH2', lambda x: auth_string)

I get error imaplib.IMAP4.error: AUTHENTICATE command error: BAD [b'[AUTHENTICATIONFAILED] AUTHENTICATE Invalid credentials']