Regarding charing % of AWS bill - yes, we're changing that soon. It's going to be flat fee + 10% of AWS bill.
Our free tier covers 90% of vibecoder, freelancer and side-project use-cases though. So probably nothing to worry about unless you're a 2+ person business. And at that point, it's still far less expensive than having a DevOps person or learning all of the 150,000 AWS loopholes yourself.