I'm not sure if we are there already. The Biden speech at the convention was very good, but the video was immediately claimed to be suspicious. The image had unusual softness around his mouth, compared to rest of the image. The speech was pre-recorded. So post processing could be responsible. But also deepfakes at this point are possible too. So who knows.

https://www.vice.com/en_us/article/7kzj8y/why-joe-bidens-vir...