Satellite 6.12.x - Custom repo where upstream is an S3 bucket

We are running Satellite 6.12 (planning to upgrade to 6.13 in near future) and have a need to serve the Kubernetes team's public RPM repository. The repository is an S3 bucket hosted at pkgs.k8s.io. Based on this documentation, this is the upstream URL: https://pkgs.k8s.io/core:/stable:/v1.30/rpm/ But Satellite throws a 403/Forbidden error trying to get the repomd.xml during sync. Any suggestions?