There doesn't seem to be a ratelimit on your most expensive ressource, the mp3 files on AWS. I checked with cURL, you can do the same. For this web app you should ratelimit the ressource aggressively because of how the game works.
Thanks for this! I'm gonna check this out
You can also consider moving to Cloudflare R2 for hosting media [1]. Egress traffic is probably going to be your biggest cost in S3.