Keycloak create user in LDAP store fails

Question

I have created a LDAP User Federation in Keycloak with Sync registration enabled.
I am trying to create a new user, with API /admin/realms/{realm}/users using following json input:

{
        "id": "2d2514b22-4cd7-4711-ae0d-529615289b58",
        "createdTimestamp": 1852647518630,
        "username":"user1",
        "enabled":true,
        "emailVerified":true,
        "firstName":"user1",
        "lastName":"user1",
        "email":"[email protected]",
        "totp": false,
        "disableableCredentialTypes": [],
        "requiredActions": [],
        "notBefore": 0,
        "access": {
            "manageGroupMembership": true,
            "view": true,
            "mapRoles": true,
            "impersonate": false,
            "manage": true
        },
        "attributes": {
        "dn": ["uid=user1,o=org12345,dc=org,dc=com"]}
    }

It throws following exception:

WARN  [org.keycloak.services.resources.admin.UsersResource] (executor-thread-107) Could not create user: org.keycloak.models.ModelException: Error creating subcontext [uid=user1,o=org12345,dc=org,dc=com]
at org.keycloak.storage.ldap.idm.store.ldap.LDAPOperationManager.createSubContext(LDAPOperationManager.java:655)
at org.keycloak.storage.ldap.idm.store.ldap.LDAPIdentityStore.add(LDAPIdentityStore.java:102)
...
Caused by: javax.naming.OperationNotSupportedException: [LDAP: error code 53 - shadow context; no update referral]; remaining name 'uid=user1,o=org12345,dc=org,dc=com'
 at java.naming/com.sun.jndi.ldap.LdapCtx.mapErrorCode(LdapCtx.java:3333)
 at java.naming/com.sun.jndi.ldap.LdapCtx.processReturnCode(LdapCtx.java:3206)
 at java.naming/com.sun.jndi.ldap.LdapCtx.processReturnCode(LdapCtx.java:2997)

How to fix above exception and get the user created in LDAP?
If Sync registration is disabled, it creates a user in Keycloack but not in LDAP server.

What am I missing here?
Keycloak: 21.1.1