Twitter is dropping the crop on web. This is the same update that banished Twitter’s awkward auto-cropping algorithm on its Android and iOS apps, which means that you’ll see images in their entirety on your timeline as you scroll through Twitter on your web browser.
You will now see an accurate preview of your image that isn't oddly styled when you publish it. The full-size preview pane on the platform is marketed as a "what you see is what you get" look at your content.
New Image Format for Influencers
The full size image takes up additional real estate on the timeline providing additional opportunities for influencers and twitter advertisers. You can take advantage of this new image format to make more compelling graphics, videos and stories.