There are also second-order giveaways that someone is using AI generation, in the case of photos the photographer would probably take numerous shots of the subject before submitting the best one, and if challenged they could produce the rest of them as evidence that they're the real deal. As far as I'm aware, using AI to generate a plausible series of photos with all of the details being consistent between them is much more difficult than generating just a single plausible photo.
In the case of artwork, the author of even the most convincing, artifact-free AI generated piece will immediately crumble if asked to show WIPs, non-flattened project files or timelapses. I have seen some charlatans attempt to fake WIPs by using style transfer to turn their finished piece back into a "sketch" but the results aren't very convincing, the models aren't trained on the process of creating art conventionally so they're not good at faking it.
In the case of artwork, the author of even the most convincing, artifact-free AI generated piece will immediately crumble if asked to show WIPs, non-flattened project files or timelapses. I have seen some charlatans attempt to fake WIPs by using style transfer to turn their finished piece back into a "sketch" but the results aren't very convincing, the models aren't trained on the process of creating art conventionally so they're not good at faking it.