@regis I also was able to fix the login issue. I had to create the application “Login Service for JWT Cookies” under Django Auth Toolkit in the Admin Panel. This application is linked to login_service_user. The client Id should be ‘login-service-client-id’
Because this user was not available or may not have been created[Refer https://github.com/edx/edx-platform/blob/master/openedx/core/djangoapps/user_authn/migrations/0001_data__add_login_service.py], the application was probably not created during migration. Hence login was failing.
After adding this application from Django Admin portal. Login is working.