Twitter has changed the image upload process so photos in JPEG format won't work.
What is known
On his account, Twitter engineer NolanO'Brien wrote about the latest changes and attached a photo as an example. Previously, when uploading pictures, images were transcoded, which caused poorer quality. Images will now be saved as JPEG encoding. Thumbnails and previews will still be compressed, and information about the location and time of shooting will be deleted.
Starting today, Twitter will preserve JPEGs as they are encoded for upload on Twitter for Web. (Caveat, cannot have EXIF orientation)
For example: the attached photo is actually a guetzli encoded JPEG at 97% quality with no chroma subsampling.https: //t.co/1u37vTopkY pic.twitter.com/Eyq67nfM0E
— Nolan O’Brien (@NolanOBrien) December 11, 2019
For now, this only works with the desktop version of Twitter, but in the future the update will come to smartphones. The developers also plan to change other images and formats.
“Other image categories (such as avatars) will receive the same improvement in the new year.” — Nolan O'Brien