What is the black bar at the bottom of the screen in these demos? Is there a way to hide it?

Hello,

Could you please post a screenshot to what you are referring to?

When posting a screenshot to these public forums please ensure you have censored any personal information.

How to take a screenshot on your iPhone, iPad, and iPod touch - Apple Support

The black bar is simply a visual “swipe” indicator for the location where you can swipe to do certain swiping gestures.

In this case, this swipe indicator is for indicating the you can swipe up to make the iPadOS Dock appear and also for a indicating short swipe up toward the center of the iPad's screen to bring up the iOS App switcher.

There are other lower “swipe”/“swiping” indicator bars when using the slide over multitasking screen to “swipe” through the various open apps in slide over view.

There used to be a swipe indicator in the upper right hand corner of the iPad's screen to indicate that swiping down from the top right corner, just below the top, black main status bar to indicate to swipe down to make the iOS Control Panel appear. That bar appears to be gone in later versions of iPadOS as my iPad does not show that particular swipe indicator bar, any longer.

These cannot be turned off, they are part of the iPadOS UI.

This has been pretty much like this since iOS 11 as a UI element as iOS/iPadOS keeps evolving and using more and more gestures in different locations, when the iPad Home button is finally gone from all iOS devices, users new to these swiping and finger gestures need to know where to do these things on new devices and new iOS/iPadOS versions.

For many these gesture/swiping indicator features are necessary to be a constantly present onscreen.

Also, the gesture and swiping features constantly change or get added to new iOS/iPadOS updates pretty regularly.

These gesture/swiping bars are easy indicators to show even experienced users if these features have changed, moved or been added to new locations.

So, these indicator bars are not going to go away or be able to be toggled ON/OFF for quite some time by Apple.

Apple introduced a few new locations for these recently.

It is what it is.