For around three years, a field of research has been developing around the detection of DeepFakes. There are two main approaches. The first involves spotting suspicious behaviour by a person in a video. An AI can be fed a large number of authentic videos of a celebrity, so that it learns to immediately detect any anomalies in their gestures or speech. The second, more general technique involves identifying the differences between DeepFakes and real videos.
Source: Artificial intelligence: DeepFake detectors have become indispensable