There was recently a case of this in a recent video of Joueur du Grenier (a French video game Youtuber). They couldn't quite him on set on time for a particula

There was recently a case of this in a recent video of Joueur du Grenier (a French video game Youtuber). They couldn't quite him on set on time for a particular scene, so at some point some guy on set said "Hey, this guy is roughly the same build as the JdG, why not have him put the costume for this scene and stand here, and deepfake the JdG's face later?". It's still a bit visible in the video though.