Ipad stuck on split screen

I have this problem, too. It definitely seems like a bug, but I can’t consistently reproduce it. I have not yet figured out if it only happens with specific app combinations.

I have figured out how to fix it, though. This is a quick fix, which takes less time that restarting my iPad Pro.

Just touch the handle at the bottom (the solid gray line at the bottom of your screen shot) and flick it up. Flick it up the same way you do to bring up the dock. Sometimes I have to flick it up twice. After doing this, the apps appear and the screen is no longer frozen.

https://support.apple.com/en-us/HT201559

here are instructions on restarting your iPad.

Try restarting your iPad,

click the down volume button and the off button at the same time and wait for the apple logo to appear

It just happened to me again.

When I got to this screen, I tried flicking up from the bottom, it went to the home screen, as it is supposed to do when you flick up from the bottom. Once I touched on Safari again, both apps came up in split view. So you can do that, or flick up and hold, as you do when bringing up the app switcher, and both apps come to life in split view.