Well, it could be done two different ways. Game engines will subtract the set blur distance from the camera and only that range is given focus, AKA depth of field. So it’s possible they did it that way, though the bokeh coloring makes me question that, as that information is harder to modify. The other more likely method which allows more control and customization is through masking frame by frame in AE. Probably through the Camera Lens Blur effect. Those would be my best guesses.