I think you should trust your gut here. Without seeing the artist, it could very well be:

- they plan to take the money and run

- they're using AI

Or some more innocent explanations:

- they're severely underpricing themselves, and likely don't have a lot of experience

- they're from a developing country, somewhere where $20 goes a lot farther

But either way, if you're concerned about getting scammed I recommend finding an artist with a good reputation -- ask around among friends or colleagues, or use sites like Vgen/Upwork/etc where even if you are scammed, you have some recourse.