iPhone X iOS 12.3.1 Keyboard switching apps

Since the download of 12.3.1, when typing on the keyboard in any app my phone will suddenly open up the app chooser, as if I had swiped up from the bottom of the screen, and select the next app. Sometimes I can catch it and stop it, but usually it just happens so fast that there's no way to stop. This has been happening consistently, but I can't recreate the effect artificially. I have noticed, however, that there's a weird delay that happens on the keyboard now, like it's trying to think while I'm typing. Also, sometimes a single key will get "stuck" after I've typed on it, with the key "raised" up above the keyboard. It persists even if I type on other keys.