OnePlus
Enable or Disable Pop-up on Keypress auf OnePlus
The little preview bubble that pops up above each key you tap is part of Gboard's key preview, not a OnePlus-specific feature. OxygenOS ships Gboard as the default keyboard, so the setting lives inside the keyboard app rather than in the general system typing menu.
Most people notice this popup while typing fast in chat apps, since every tapped letter briefly appears larger above the keyboard. Some find it helpful for confirming accuracy on a small screen, others see it as visual clutter that slows down typing.
To change it, go to Open the Settings ➔ Tap on System ➔ Tap on Languages & input ➔ Tap on Virtual keyboard ➔ Tap on Gboard ➔ Tap on Text correction ➔ Enable or disable Popup on keypress.
Turning the toggle off removes the key preview immediately, with no restart needed. Autocorrect, word suggestions, and swipe typing keep working exactly as before, since the popup is a purely visual effect.
If you use a different keyboard app instead of Gboard, this setting will not apply, and you need to check that app's own typing or keyboard preferences.