Another insight: do backups. If you have one, now is the time to use it.
If you don’t, let’s try to reset LDAP. This is untested:
sudo su
source /usr/share/yunohost/hooks/conf_regen/06-slapd
# Should reset slapd
do_init_regen
#Here make sure ldap works again. If not try
yunohost tools regen-conf slapd -f
#Recreate your users now
#yunohost user create <user>
#Assign at least one to be admin
#yunohost user group add admins <user>
#Since ldap base is empty, let's regenerate the apps permissions by force-upgrading them
#Sorry for having you rebuild whole apps, there surely is a way to only update the permissions but this is faster to write
for a in $(yunohost app list --output-as json | jq -r '.apps[]|.id'
do
yunohost app upgrade $a --force
done
If it’s still failing, still report the errors you see here, but I am out of ideas.