How to control little recent-window thumbnails that appear in iPad apps

I don’t even know what to call these things, which makes searching for a solution difficult. I’ve tried. A lot.

They look like little thumbnail images of recent windows. They appear on the screen, near the bottom, hovering in front of the app until I tap somewhere. Then they all slide away.

What are they? Is it possible to make them stop appearing or at least to control them? Or even find out what they’re called?

Sometimes I go for weeks without seeing them, and then suddenly they’ll start appearing in some apps but not in others. I have no use for them.

Today they’re showing up in DevonThink:

But they also arbitrarily show up in Safari, Mail, Pages, Numbers, etc.

Thanks for your advice.

These are multiple windows open from the same app. You can dismiss them (apart from the one you have open) by swiping them up.

But they’re doing no harm by being open. The OS will manage them and ensure they’re not taking up memory by freezing them after a period of time.

Thanks. I didn’t know I could swipe them away. That helps.

I ignored them until they did start doing a kind of harm — occasionally covering the very thing I want to tap first when I open the app. Doesn’t happen a lot, but every time it happens, I wonder (sometimes out loud, with colorful language) why I have to move a thing I never use out of the way so that I can do the thing I came to do.