Change user id in keycloack

Hello
I use Keycloak version 17
I have migrate a keycloak installation from on VM to another using the import /export Realms function.
My keycloak serve an nextcloud login.
My Keycloak get the user from an openldap server

But in the new Keycloak I get new ID for all user…
And Nexcloud use this ID to identify the login user.
=> now when connecting to nextcloud, all user have a new empy account… (the old account exist but is no more accessible through keycloak login)

Is there a way to change the ID number of a user ?
I did not found a way in the web interface.
Is it possible directly in the database?

Thanks