This is a very interesting anecdote considering the m1 IPad Pro is supposed to have one of the best screens available on any device that form factor, the same XDR display technology as their $5000+ monsters. Every reviewer has mentioned the display as the selling point. I have looked at them in person and have debating buying one, but Next time I’m at an Apple Store I’ll want to see if I can replicate what you’re seeing.

You might be experiencing the mini-LED effect where the back lighting is regionalized, which isn’t ghosting but can be noticeable.