NCP doesn’t appear to check for the latest version correctly.
This is what it shows when trying to update nextcloud through NCP:
[ nc-update-nextcloud ] Current Nextcloud version 18.0.5.1 Available Nextcloud version 18.0.4 Nothing to update
I had to update in nextcloud, but even prior when I was on 18.0.4, it didn’t detect 18.0.5.1