Why did my passwords disappear on iPad 9 after updating to iOS 18.3.1?

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.

Try deleting the Passwords App from your iPad (don't worry, your saved Passwords are still safely stored in iCloud).

Remove or delete apps from iPad - Apple Support

Having removed the Passwords App, restart your iPad:

Force restart iPad - Apple Support

After the iPad restarts, re-install the Passwords App from the App Store:

https://apps.apple.com/app/passwords/id6473799789

Just to be clear...

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)

The workaround suggested by Chuck seems to work. The three dots are right at the top of the screen in the centre. Try to open ‘Passwords,’ ignore the instruction for touch security, tap the three dots and at the foot of the screen, tap ‘New Window’ at the right hand end. Passwords should now open.