In the Oldje days ... ISO 800 film was made purposely to be grainy. I didn't know what that purpose was ...
I think it was made purposely to be fast, and that resulted in grain. Some photographers used it because they like the look of grain, but its purpose was low light photography.
Some of the newer AI software offers an option to "add grain" but I'm thinking this one doesn't really need it. Maybe just a little milk and sugar?
That seems odd. It's like giving video that old, grainy, splotchy look, with lines running through the video. That can be done briefly for effect, but not continuously.