Maybe it picked up a glitch and a hard reset is needed with holding the Volume down and power keys, giving it a chance to reset.
But, if that doesn't work, still, the best keyboard I've ever used is now the Microsoft SwiftKey keyboard. It will learn your typing style better than anything I've used, and is very feature-rich and customizable. It's been my keyboard ever since I went to Android back in 2012.
It Swipes well, too. I'm a Note 9 user, also.