I am going to post several screenshots when using Mail and Notes, but in preparing those for you, the water really got muddy and I'm going to confuse the issue trying to explain.
When using the keyboard in landscape mode when replying to an existing email, there is no fullstop on the keyboard, but typing using the lower case ? key, it types a fullstop.
When using the keyboard in landscape mode when creating a NEW email, the fullstop is displayed on the keyboard by itself.
When using the keyboard in landscape mode in Notes, the fullstop is never displayed, but again, typing using the lower case ? key, it types a fullstop.
This is my wife's ipad, so I have not tried changing the screen resolution to see if that fixes the problem. Will try that later.