Hi,
Anyone who access the UpdraftPlus admin page can take, and download, a database backup. So, keeping passwords in the WP database only, and not on the page, makes zero difference to the ability of people viewing the page to get the passwords. Worse – if they can reach the backup page, then they can upload their own backup, and entirely replace the complete site. So, if there’s someone whom you don’t trust, then don’t let them reach an admin page where they can take and restore backups. If you can’t prevent someone being an admin, but want them not to reach the page, then there is this: https://updraftplus.com/faqs/want-lock-updraftplus-settings-site-admins-access/
David