Old LDAP trying to connect to new Nextcloud

Nextcloud version (eg, 20.0.5): 21.0.4
Operating system and version (eg, Ubuntu 20.04): Ubuntu 20.04
Apache or nginx version (eg, Apache 2.4.25): 2.4.41 (Ubuntu)
PHP version (eg, 7.4): 8.0.3

The issue you are facing:
So, our company runs an internal Nextcloud which we siwtched out yesterday for a newer better configured Nextcloud with a new LDAP connection (AD change).
In this switch we replace our old Nextcloud’s domain to nextcloud-old and replace the new one to the original nextcloud’s domain.
The problem is that everyone that is connected to our old nextcloud with the old doamin (and ad) is still trying to connect to the new Nextcloud with the old LDAP login and is slowing down the new nextcloud server.

Old login credetials trying to log in to new nextcloud which have new login credentials (Mobile and desktop app)

Is this the first time you’ve seen this error? (Y/N):

Steps to replicate it:

  1. Have an old and a new Nextcloud
  2. Replace the new nextclouds with the old ones
  3. Login credential problems from the old logins

The output of your Nextcloud log in Admin > Logging:
Screenshot 2021-09-22 095711

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
Would not be needed here.

The output of your Apache/nginx/system log in /var/log/____:
Would not be needed here.