HOW AN EMPTY S3 BUCKET CAN MAKE YOUR AWS BILL EXPLODE

Summary from the TLDR Web Dev newsletter

An S3 bucket can lead to a massive AWS bill, even when it's empty. AWS charges for all S3 requests, including unauthorized ones (4xx errors), meaning someone trying to mistakenly write to your bucket still incurs costs for you. Misconfigured open-source tools and S3 requests without a specified region can also create unexpected costs that add up.