Hi @RyanJarv , I got a ticket about this issue internally. Thanks for raising the issue to us. Unfortunately RubyGems.org does not support namespacing of gems, so technically anyone can reserve aws-sdk-foo gems. In this case, STS service is already established but no such V3 gem (aws-sdk-sts) existed because it was designed to live in aws-sdk-core.
With your permission, we will own this gem and make it an alias of aws-sdk-core (since STS is included in core). This would work the same way as aws-sdk-sso. It would not raise an error. It would be published as version 1.0.0 in line with the other SDK gem versions.