FROM mirror.gcr.io/{image_name}
We received failed to resolve source metadata for mirror.gcr.io/
So it looks like these services may not be true mirrors, and just functioning as a library proxy with a cache. FROM public.ecr.aws/docker/library/{image_name}
In the error logs, the issue was mostly related to the authentication endpoint:
Some restore options also do not let you move data to their cloud for direct download, which makes it feel like they do not actually want users to fully download and recover all of their files.