Missing 'Passwords' item after OS upgrade

Expanding upon stedman1’s reply...

Passwords saved in your keychain are no longer accessed from device settings. For iOS/iPadOS18, saved Passwords and account credentials are now accessed using the new Apple Passwords App; when you updated to iOS/iPadOS18, this new App will have been automatically installed on your device.

This support page may be of interest:

Use the Passwords app to create, manage, and share passwords and passkeys across Apple devices - Apple Support

The iPad User Guide is a rich (and often overlooked) source of information about your iPad and iPadOS. Here is direct link to the relevant section of the Guide:

View your passwords and related information on iPad - Apple Support

The Tips App, installed by default on all new models of iPad, provides a brief introduction - and leads you to the User Guide. In case you missed it, here is a link to the Tips App:

https://apps.apple.com/app/tips/id1069509450

It is now a stand alone app as opposed to being part of the Settings menu. Check the last page for it.