The current default installation, especially if using Ansible, doesn't use any commercial image hosting services. You need to go out of the golden path to do so.

Even using an S3-compatible host is not in the default path: the files are stored to the server file system. So, yeah, maybe this is the reason. And of course, giving your content to a commercial entity is something people in the fediverse doesn't like that much. Wasn't the idea to get rid of these entities that can just be bought by a billionaire asshole and suddenly killing your community.