aggravating On-Screen Keyboard Popups

I have no idea what I'm doing to cause this. When I am typing with the on-screen keyboard on the iPhone7, it frequently makes a sound, like the double tap and hold sound, and a bunch of word suggestions come up in place of the keyboard. I have to slide my finger to the top of the screen and remove it to get them to go away, otherwise it inserts one of the words. In some apps, like Scrivener, it inserts a space even if I do that.
I turned off 3D, but it still happens.
How am I causing this, and how do I turn it off?