iPad notes gone after iOS 15.6 update

See >>> If you're missing notes on your iPhone, iPad, or iPod touch - Apple Support

Performing a forced-restart of your iPad may be helpful:

• 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.