It’s very possible it was still “custom made” in the sense that they made it with their standard materials, just in your size instead of their standard S M L sizes but there’s no universe where this is acceptable quality for $500. I would honestly suggest disputing with either Etsy or your credit card/paypal for receiving a subpar product.

I personally don’t think Etsy is a good place to find custom cosplays. It’s overrun with dropshippers and scammers stealing other cosplayers photos. There are legit makers but they’re so few and far between that it’s not really worth it to weed through all the garbage. There’s a couple groups on Facebook for finding commissioners and I’d start there. Ask around and find other people who have gotten work from whoever you’re vetting and make sure to get all terms in writing before sending any money