this doesn’t embed anything and is listed as the first embed plugin for github

Hi;

Are you actually experiencing a bug here? The screenshots on the plugin page show what is embedded : https://wordpress.org/plugins/github-embed/#screenshots

Are you saying that this isn’t working for you?

Hi;

The purpose of this plugin is to act as an oEmbed proxy for GitHub, allowing users to easily include rich, formatted information about a repo, user, milestone etc. into their posts and pages by simply pasting in the relevant URL.

It does that as-designed as per the screenshots you provided.

While that behaviour might not be what you’re looking for, and if so, it sounds like this isn’t the plugin for you.

While I’m sorry to hear that, I’m not sure leaving a 1-star review is appropriate just because the plugin doesn’t do what you want and I’d ask you to reconsider that.