SwiftKey updated its beta app to fix a bug that rendered the key fonts and icons hardly readable for some Android Marshmallow preview builds. Now, it’s back to normal size, making it easier for you to type/swipe away on your keyboard. The latest beta also stops support for Gingerbread or other older devices. If you’re interested in being part of the SwiftKey beta program, you have to join this Google Group and select the “Become a Tester” link.
Source: Android Police