There are a few apps (including at least the stock Android 'Messaging' app, and Bumble) in which when I myself (or other people) type :), I see a blushing face emoji instead. Why does this sort of thing happen, and can you stop it?
Why does it happen?
Because the app renders such text as an emoji. Users of old MSN (or new Facebook) are more or less used to it. The app reads the text, sees a specific string of characters like
:) and replaces it with the emoji it is linked to.
Can you stop it?
Depends on the app. Far as I know, stock messaging apps usually offer the option to turn it off. But third party apps might or might not.