Please perform the clear cache of the Samsung keyboard app on your phone.
Go to Settings>>Tap Apps>>Select the Samsung keyboard app>>Tap the Storage option>>Tap on Clear cache.
Then follow the suggestions provided by Cassidy and check if it works.
Go to Settings>>Tap on Sounds and vibration>>Select System sounds and vibration>>Tap the Samsung Keyboard>> Disable it.
Thanks, Cassidy for your information.