This is the norm for Debian, including their own mystery meat in every package without asking upstream, and then making it look like an official release. I remember there was a post about that from the Redis guy a few days ago.

The guy who made those Docker images is not to blame in my opinion because he just trusted Debian, which is a renowned distro; he expected them to do the right thing. I believe Debian has a good reputation that they don't deserve anymore.