Thanks for the screenshots - as these do help to understand what’s going-on.
As now illustrated, you have closed all windows but one - now confirming that you don’t have a second active window. If a draft now appears whenever you launch the Mail App, I’m stumped.
Perhaps perform a forced-restart of your iPad - as so doing will often resolve an isolated software issue:
- On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
- On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.
Otherwise, I can only suggest seeking assistance directly from Apple Support, or the Genius Bar as previously recommended.
You can contact the Support Team using the Get Support link at top-right 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/gb/app/apple-support/id1130498044