My passwords disappeared from settings on last upgrade

Having updated to iOS/iPadOS 18.x, you will not find your saved Passwords in iPhone or iPad device settings. All saved passwords have been migrated to the new Passwords App which you will find on one of your Home Screens, or from the App Library.

If you only see a blank page when you open the Passwords App, assuming that the Passwords App has been added to the Dock...

With the Passwords App open to the blank page, swipe upwards from the bottom of the screen to expose the Dock - tap the Password App icon - then tap New Window. This should open another Passwords App window showing your stored Passwords.

(NB: This screenshot illustrates the New Window button - but otherwise shows the Passwords App as it should appear)

You must have done something during the update. Do you have a backup for the iPad hard drive?