iPad not saving passwords or updating passwords

To have any idea or explanation of “why” would first require an understanding of “what” has caused a change in functionality. Unfortunately, there’s insufficient information of the latter for an explanation as to the former.

If your iPad is not functioning as expected, try a forced restart - as this will often clear an isolated software issue:

Force restart iPad (models with Face ID or with Touch ID in the top button)

If your iPad doesn’t have the Home button, do the following:

1. Press and quickly release the volume button nearest to the top button.
2. Press and quickly release the volume button farthest from the top button.
3. Press and hold the top button.
4. When the Apple logo appears, release the top button.

Force restart iPad (models with the Home button)

Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.

See:

If iCloud Keychain won't turn on or sync - Apple Support

If you continue to experience difficulties, you would be best advised to seek assistance directly from from Apple Support. You can contact the Support Team using the Support link at top-right or bottom-left of this page.

Alternatively, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/app/apple-support/id1130498044