Turn off hide my email

You're very welcome.

The entire point of the Hide My Email feature is for those situations where you choose (or have no other option than) to provide an email address to someone - but don't wish to reveal your real address. Hide My Email allows you to create a temporary/disposable email address to use in place of your real email address; as soon as it has served its purpose, you de-activate the associated Hide My Email address - and any email addressed to it will never bother you again.

The iPad User Guide provides more information:

Create and manage Hide My Email addresses in Settings on iPad - Apple Support

I'm unsure what you are actually seeing. Can you post a screenshot of precisely what you see? A picture might aid the understanding of both myself and other contributors:

Take a screenshot on your iPad - Apple Support

Before posting your screenshot here, ensure that you have first redacted any personal information/email addresses using markup tools. When ready, you can post your screenshot using the image button - found at the bottom of the message editing window:

To be clear, you can't "hide" the function, but you don't need to use it.

Perhaps your difficulty relates to your Autofill settings not being correct - as it is this function that automatically populates your actual email address and other details within web forms. The related button for Autofill is illustrated in your first posted screenshot.

For AutoFill functions and setup, see:

Automatically fill in forms in Safari on iPad - Apple Support

Automatically fill in strong passwords on iPad - Apple Support

The feature is disabled - unless you have added one or more Hide My Addresses.

Removing all configured addresses again disables the feature.

You "turn-off" the Hide My Email feature by individually deleting all of the Hide My Email addresses that you have created:

Settings > [Your Name / AppleID] > iCloud > Hide My Email - tap the address to be deleted, then select Deactivate email address

Repeat for all remaining addresses.

The Hide My Email option offered at top-centre of the onscreen keyboard (first image) provides an easy method to either (a) create a new Hide My Email address - and/or use an existing Hide My Email address when populating the box that appears above. This is entirely as expected. You will only use this button if you intend to use a Hide My Email address.

The second image above shows that you don't have any preconfigured Hide My Email addresses - but can create one (should you wish to do) so using the blue Create New Address button.

You'll also note the Autofill Contact option at top-left of the onscreen keyboard - which, if chosen, will instead populate the box with your actual contact details (from your own Contact Card within the Contacts App) including your real email address. Again, this is entirely as expected - and is used to quickly and automatically populate a form with your real details.

Your third option is to manually enter details of your choice - using the Keyboard.

In summary, your iPad appears to be working entirely as expected - illustrating the integrated nature of iPadOS and some of its many features.

What you see in the last screenshot is exactly as expected. The Hide My Email button seen at top-centre of the on-screen keyboard is a shortcut button to setting-up a new, or using an existing, Hide My Email address. In circumstances that you don't wish to use it, don't select it.

Instead of using the shortcut to the Hide My Email page, simply type the address that you do wish to use when populating the form that you see on the webpage.