Oof, as someone who does some writing and understands AI I would never. Not just because it would be giving up any rights to my work but because the AI is programmed to have an opinion. That means it's going to give you a canned range of feedback so that it feels real. The feedback is not necessarily real. In fact it's probably not. I would be unsurprised to submit a story with two characters and get the same line about three characters.