Germany has a strong culture of political impersonation cabaret, so we see this a digital version. It just has to be identifiable as a fake.
It's acting, not lying.
Well, I suppose you could argue that acting is always lying.
Discussion
In acting, the audience knows that they're seeing an actor, not the real person. That's the difference.
Deepfakes present themselves as the real person, in some cases.
That's why they have to be identifiable, by law.
Otherwise, the acting can be too convincing.
Like having a lifelike puppet.