Originally Posted by El_Duderito

For those that have any kind of issues on Android make sure that you upgrade to version 4.57 (or later once they come out).
4.57 introduced a bot protection feature for a list of API endpoints and those clients (i.e. older Android apps) that are not aware of this will receive the 403 Forbidden error message that popped up here.
Users of older Android apps should receive a notification that a new release is available when starting the app.