The version my friends sent to me yesterday was definitley edited with AI; in the post you provided the card says Hello Merrymonder which is a Korean fashion brand whereas my copy it’s gibberish. Guess I should have dug further for an original.

Just curious, what process did you use to turn up her Instagram post?

Well, it's already easy to make a visually convincing fake photo if you're motivated to do so. For this picture, some local models do make more convincing text, but if the angle and stylization are still too much, you could also just remove the tell entirely by asking for the napkin to be removed, replaced with another object, or changed to a flat color, floral design, etc. Tells only still exist at the point because the prompter either doesn't care or doesn't know.

It’s getting a lot more challenging to tell; certainly not immediately obvious like it used to be

Some sweaters can look like that, especially in low-contrast colors and slightly blurry photos.