outline
If you got about 20 ~ 50 dollars of invoice e-mail from AWS not for monthly billing, it could be Amazon Registar billing for Renewing registration for a domain you bought, before. But, you can NOT check detail from invoice e-mail, itself.
checking-detail-of-invoice
From invoice, you can check the timing of billed and you can cross check requests from "AWS Route53 >> Domains >> Requests" . You can compare the timing of invoice and domain requests. The other way, you can use "Download billing report" button from right upper side of "AWS Route53 >> Registered domains".
reference
https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/domain-billing-report.html