If the initial setting for isSendButtonDisabled is false, when the user types in the input component and hits enter, onSendMessage is not called.
This is likely due to to the handleKeyDown callback not having the correct dependencies:
https://github.com/patternfly/chatbot/blob/main/packages/module/src/MessageBar/MessageBar.tsx#L126-L135
The eslint settings should be updated to warn when all necessary dependencies are not included.