iPad: Apple Notes partially blocked by toolbar in landscape view.

Are you aware that the markup toolbar can be dragged to a different position on the screen - or be minimised?

Show, move, and hide the Markup toolbar

To show the Markup toolbar in a supported app, tap  or Markup, then do any of the following:

• Move the Markup toolbar: Drag the toolbar to any edge of the screen.
• (Drag from the middle edge of the toolbar closest to the center of the screen.)
• Automatically minimize the toolbar when you’re drawing or entering text: Tap , then turn on Auto-minimize.
• To show the full toolbar again, tap the minimized version.
• Hide the toolbar: Tap  or Done.

See:

Draw in apps with Markup on iPad - Apple Support

For much newer design iPad models, without a Home button, try the new simple hard reset/forced restart procedure for the new 2018-2022 iPad Pros, 2020/21 iPad Air 4 and 5, the 2021 iPad Mini 6 models and the new 2022,,10th gen base models,

1. Press and release the volume button closest to the top Power button

2. Then immediately press and release the volume button farthest from the top Power button.

3. Then, press and hold the top single sleep/wake/power button You will see the Slide to Power off button, but keep on holding down the power button until you see the Apple logo, then let it go.

Once you have performed all the steps, wait for a few seconds and your 2018-2022 iPad will boot up completely to the iPad’s Lock screen.

Best of Luck to You!