When determining if the media has been deceptively altered, Twitter will consider factors like whether a real person has been fabricated. It may flag content if visual or auditory info (like dubbing) has been added or removed. It will also judge the context and whether the deepfake is likely to impact public safety or cause serious harm.
Beginning March 5th, Twitter may label Tweets with "deceptively altered or fabricated content." It may also show a warning to people before they retweet or like the manipulated media, reduce the visibility of the tweet, prevent it from being recommended or provide additional explanations through a landing page.
These changes are the result of an effort to combat deepfakes. Twitter promised these rules late last year, and it drafted guidelines based on user feedback. The platform has already banned porn deepfakes, and as the 2020 election nears, it's likely Twitter wants to prevent political deepfake scandals and misinformation campaigns.