Deepfakes are still a relatively new phenomenon, having first appeared in December 2017.

Deepfakes are still a relatively new phenomenon, having first appeared in December 2017. Thus far their range of illicit use stretches from harmless mischief (putting Nick Cage's face in every movie ever made) to potential harassment (overlaying the faces of celebrities into porn videos).

http://lscottharrell.blogspot.com/2018/04/deepfake-video-forensics.html

deepfake fake celebrity pornography
At present, a deepfake can still be easily spotted by the untrained eye. The effect is impressive, but there are still obvious artifacts and inconsistencies in most of these videos that make it clear they have been doctored.

That won't always be the case, however.