On June 1 we are upgrading the way we scale the images you upload to Twitter, resulting in higher quality landscape images being returned by our REST API. For more details including examples of the change, please refer to our blog post announcement.
You should check that your code does not make assumptions based on the current sizing limits. Older versions of Twitter Kit for iOS do not properly support the change, so you are encouraged to upgrade to v2.0 or v1.15.3 to avoid a regression in image quality.
For any questions regarding this update, please take advantage of either the REST API or Fabric Twitter Kit categories depending on your development.