Stable release of Config Split 2.x using the configuration transformation API fron Drupal core instead of Config Filter
If you have not explicitly required Config Filter before, Composer will remove it when updating. But then you are left with a drupal module still being installed but no longer available in the code base.
In order to properly uninstall Config Filter you should explicitly require it and then uninstall it, and remove it from composer.json only in a later deployment.
This would be 2.0.0-rc1 if it wasn't for the missing test coverage
Lots of new things for you to enjoy compared to beta 2. There is an update hook to upgrade from 1.x and from 2.0.0-beta2. The behavior changes a bit, see also the Nuvole blog post.