Migrate to bookworm could not be completed (nsswitch & ldap)

Warning: The configuration file ‘/etc/nsswitch.conf’ has been manually modified and will not be updated

Ah yes sorry that should be : yunohost tools regen-conf nsswitch --force

(and actually you probably want yunohost tools regen-conf --force to force-regen everything because i doubt you really manually modified slapd.ldif and ntp.service.d/ynh-override.conf)