There is a couple of cgs I had drawn in person including this one for a plan, I had painted it and scanned it in, then I used an editing software to make it look way better, including without disturbances in the background.
I have no doubt that the sketches you've shown aren't ai, but the pictures in the preview are ai altered. Many editing software uses ai. They make you choose a theme and they'll use ai to alter the image according to what you chose. Just informing you.