What is this screen format?? Make it stop!

My IPad Pro started showing this screen when I open a new app.

The new app opens in this new format, not full screen, and I either have to use the 3 dots at the top or the little logo in the bottom right corner of the new app to make it full screen.

You cannot swipe the open app ⬆️⬇️⬅️➡️ but tapping one of the small ones on the left will switch to it but it will still not be full screen.

To get out of this screen completely I have to swipe up from bottom to get the app changer before I can do anything else.

Is this new or something I’ve turned on by mistake and is there a way to turn this off?

It is very, very, very annoying.

I just want an app to open full screen when I push it… not get the choices of the apps I have open.

I do have the latest update… I assume this is something someone thought was brilliant but is just aggravating.

I await all your knowledgeable advice.