What is the name of the keyboard you are using?
We would suggest that you clear storage and cache of the keyboard.
Settings > Apps & notifications > See all apps > Find your keyboard app > Storage & memory > Clear cache & storage.
If the problem is still appearing, could you show us a short video of the problem?
To share videos, please upload it to ASUS WebStorage (https://www.asuswebstorage.com/navigate/) and share the link with us.
Thank you 🙂